afnetworking

/**
 The managed session.
 */
@property (readonly, nonatomic, strong) NSURLSession *session;

/**
 The operation queue on which delegate callbacks are run.
 */
@property (readonly, nonatomic, strong) NSOperationQueue *operationQueue;

/**
 Responses sent from the server in data tasks created with `dataTaskWithRequest:success:failure:` and run using the `GET` / `POST` / et al. convenience methods are automatically validated and serialized by the response serializer. By default, this property is set to an instance of `AFJSONResponseSerializer`.

 @warning `responseSerializer` must not be `nil`.
 */
@property (nonatomic, strong) id <AFURLResponseSerialization> responseSerializer;

///-------------------------------
/// @name Managing Security Policy
///-------------------------------

/**
 The security policy used by created session to evaluate server trust for secure connections. `AFURLSessionManager` uses the `defaultPolicy` unless otherwise specified.
 */
@property (nonatomic, strong) AFSecurityPolicy *securityPolicy;

#if !TARGET_OS_WATCH
///--------------------------------------
/// @name Monitoring Network Reachability
///--------------------------------------

/**
 The network reachability manager. `AFURLSessionManager` uses the `sharedManager` by default.
 */
@property (readwrite, nonatomic, strong) AFNetworkReachabilityManager *reachabilityManager;
#endif

///----------------------------
/// @name Getting Session Tasks
///----------------------------

/**
 The data, upload, and download tasks currently run by the managed session.
 */
@property (readonly, nonatomic, strong) NSArray <NSURLSessionTask *> *tasks;

/**
 The data tasks currently run by the managed session.
 */
@property (readonly, nonatomic, strong) NSArray <NSURLSessionDataTask *> *dataTasks;

/**
 The upload tasks currently run by the managed session.
 */
@property (readonly, nonatomic, strong) NSArray <NSURLSessionUploadTask *> *uploadTasks;

/**
 The download tasks currently run by the managed session.
 */
@property (readonly, nonatomic, strong) NSArray <NSURLSessionDownloadTask *> *downloadTasks;

///-------------------------------
/// @name Managing Callback Queues
///-------------------------------

/**
 The dispatch queue for `completionBlock`. If `NULL` (default), the main queue is used.
 */
@property (nonatomic, strong, nullable) dispatch_queue_t completionQueue;

/**
 The dispatch group for `completionBlock`. If `NULL` (default), a private dispatch group is used.
 */
@property (nonatomic, strong, nullable) dispatch_group_t completionGroup;

///---------------------
/// @name Initialization
///---------------------

/**
 Creates and returns a manager for a session created with the specified configuration. This is the designated initializer.

 @param configuration The configuration used to create the managed session.

 @return A manager for a newly-created session.
 */
- (instancetype)initWithSessionConfiguration:(nullable NSURLSessionConfiguration *)configuration NS_DESIGNATED_INITIALIZER;

/**
 Invalidates the managed session, optionally canceling pending tasks and optionally resets given session.
 
 @param cancelPendingTasks  Whether or not to cancel pending tasks.
 @param resetSession        Whether or not to reset the session of the manager.
 */
- (void)invalidateSessionCancelingTasks:(BOOL)cancelPendingTasks resetSession:(BOOL)resetSession;

///-------------------------
/// @name Running Data Tasks
///-------------------------

/**
 Creates an `NSURLSessionDataTask` with the specified request.

 @param request The HTTP request for the request.
 @param uploadProgressBlock A block object to be executed when the upload progress is updated. Note this block is called on the session queue, not the main queue.
 @param downloadProgressBlock A block object to be executed when the download progress is updated. Note this block is called on the session queue, not the main queue.
 @param completionHandler A block object to be executed when the task finishes. This block has no return value and takes three arguments: the server response, the response object created by that serializer, and the error that occurred, if any.
 */
- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request
                               uploadProgress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock
                             downloadProgress:(nullable void (^)(NSProgress *downloadProgress))downloadProgressBlock
                            completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject,  NSError * _Nullable error))completionHandler;

///---------------------------
/// @name Running Upload Tasks
///---------------------------

/**
 Creates an `NSURLSessionUploadTask` with the specified request for a local file.

 @param request The HTTP request for the request.
 @param fileURL A URL to the local file to be uploaded.
 @param uploadProgressBlock A block object to be executed when the upload progress is updated. Note this block is called on the session queue, not the main queue.
 @param completionHandler A block object to be executed when the task finishes. This block has no return value and takes three arguments: the server response, the response object created by that serializer, and the error that occurred, if any.

 @see `attemptsToRecreateUploadTasksForBackgroundSessions`
 */
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request
                                         fromFile:(NSURL *)fileURL
                                         progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock
                                completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError  * _Nullable error))completionHandler;

/**
 Creates an `NSURLSessionUploadTask` with the specified request for an HTTP body.

 @param request The HTTP request for the request.
 @param bodyData A data object containing the HTTP body to be uploaded.
 @param uploadProgressBlock A block object to be executed when the upload progress is updated. Note this block is called on the session queue, not the main queue.
 @param completionHandler A block object to be executed when the task finishes. This block has no return value and takes three arguments: the server response, the response object created by that serializer, and the error that occurred, if any.
 */
- (NSURLSessionUploadTask *)uploadTaskWithRequest:(NSURLRequest *)request
                                         fromData:(nullable NSData *)bodyData
                                         progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock
                                completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler;

/**
 Creates an `NSURLSessionUploadTask` with the specified streaming request.

 @param request The HTTP request for the request.
 @param uploadProgressBlock A block object to be executed when the upload progress is updated. Note this block is called on the session queue, not the main queue.
 @param completionHandler A block object to be executed when the task finishes. This block has no return value and takes three arguments: the server response, the response object created by that serializer, and the error that occurred, if any.
 */
- (NSURLSessionUploadTask *)uploadTaskWithStreamedRequest:(NSURLRequest *)request
                                                 progress:(nullable void (^)(NSProgress *uploadProgress))uploadProgressBlock
                                        completionHandler:(nullable void (^)(NSURLResponse *response, id _Nullable responseObject, NSError * _Nullable error))completionHandler;

///-----------------------------
/// @name Running Download Tasks
///-----------------------------

/**
 Creates an `NSURLSessionDownloadTask` with the specified request.

 @param request The HTTP request for the request.
 @param downloadProgressBlock A block object to be executed when the download progress is updated. Note this block is called on the session queue, not the main queue.
 @param destination A block object to be executed in order to determine the destination of the downloaded file. This block takes two arguments, the target path & the server response, and returns the desired file URL of the resulting download. The temporary file used during the download will be automatically deleted after being moved to the returned URL.
 @param completionHandler A block to be executed when a task finishes. This block has no return value and takes three arguments: the server response, the path of the downloaded file, and the error describing the network or parsing error that occurred, if any.

 @warning If using a background `NSURLSessionConfiguration` on iOS, these blocks will be lost when the app is terminated. Background sessions may prefer to use `-setDownloadTaskDidFinishDownloadingBlock:` to specify the URL for saving the downloaded file, rather than the destination block of this method.
 */
- (NSURLSessionDownloadTask *)downloadTaskWithRequest:(NSURLRequest *)request
                                             progress:(nullable void (^)(NSProgress *downloadProgress))downloadProgressBlock
                                          destination:(nullable NSURL * (^)(NSURL *targetPath, NSURLResponse *response))destination
                                    completionHandler:(nullable void (^)(NSURLResponse *response, NSURL * _Nullable filePath, NSError * _Nullable error))completionHandler;

/**
 Creates an `NSURLSessionDownloadTask` with the specified resume data.

 @param resumeData The data used to resume downloading.
 @param downloadProgressBlock A block object to be executed when the download progress is updated. Note this block is called on the session queue, not the main queue.
 @param destination A block object to be executed in order to determine the destination of the downloaded file. This block takes two arguments, the target path & the server response, and returns the desired file URL of the resulting download. The temporary file used during the download will be automatically deleted after being moved to the returned URL.
 @param completionHandler A block to be executed when a task finishes. This block has no return value and takes three arguments: the server response, the path of the downloaded file, and the error describing the network or parsing error that occurred, if any.
 */
- (NSURLSessionDownloadTask *)downloadTaskWithResumeData:(NSData *)resumeData
                                                progress:(nullable void (^)(NSProgress *downloadProgress))downloadProgressBlock
                                             destination:(nullable NSURL * (^)(NSURL *targetPath, NSURLResponse *response))destination
                                       completionHandler:(nullable void (^)(NSURLResponse *response, NSURL * _Nullable filePath, NSError * _Nullable error))completionHandler;

///---------------------------------
/// @name Getting Progress for Tasks
///---------------------------------

/**
 Returns the upload progress of the specified task.

 @param task The session task. Must not be `nil`.

 @return An `NSProgress` object reporting the upload progress of a task, or `nil` if the progress is unavailable.
 */
- (nullable NSProgress *)uploadProgressForTask:(NSURLSessionTask *)task;

/**
 Returns the download progress of the specified task.

 @param task The session task. Must not be `nil`.

 @return An `NSProgress` object reporting the download progress of a task, or `nil` if the progress is unavailable.
 */
- (nullable NSProgress *)downloadProgressForTask:(NSURLSessionTask *)task;

///-----------------------------------------
/// @name Setting Session Delegate Callbacks
///-----------------------------------------

/**
 Sets a block to be executed when the managed session becomes invalid, as handled by the `NSURLSessionDelegate` method `URLSession:didBecomeInvalidWithError:`.

 @param block A block object to be executed when the managed session becomes invalid. The block has no return value, and takes two arguments: the session, and the error related to the cause of invalidation.
 */
- (void)setSessionDidBecomeInvalidBlock:(nullable void (^)(NSURLSession *session, NSError *error))block;

/**
 Sets a block to be executed when a connection level authentication challenge has occurred, as handled by the `NSURLSessionDelegate` method `URLSession:didReceiveChallenge:completionHandler:`.

 @param block A block object to be executed when a connection level authentication challenge has occurred. The block returns the disposition of the authentication challenge, and takes three arguments: the session, the authentication challenge, and a pointer to the credential that should be used to resolve the challenge.

 @warning Implementing a session authentication challenge handler yourself totally bypasses AFNetworking's security policy defined in `AFSecurityPolicy`. Make sure you fully understand the implications before implementing a custom session authentication challenge handler. If you do not want to bypass AFNetworking's security policy, use `-setAuthenticationChallengeHandler:` instead.

 @see -securityPolicy
 @see -setAuthenticationChallengeHandler:
 */
- (void)setSessionDidReceiveAuthenticationChallengeBlock:(nullable NSURLSessionAuthChallengeDisposition (^)(NSURLSession *session, NSURLAuthenticationChallenge *challenge, NSURLCredential * _Nullable __autoreleasing * _Nullable credential))block;

///--------------------------------------
/// @name Setting Task Delegate Callbacks
///--------------------------------------

/**
 Sets a block to be executed when a task requires a new request body stream to send to the remote server, as handled by the `NSURLSessionTaskDelegate` method `URLSession:task:needNewBodyStream:`.

 @param block A block object to be executed when a task requires a new request body stream.
 */
- (void)setTaskNeedNewBodyStreamBlock:(nullable NSInputStream * (^)(NSURLSession *session, NSURLSessionTask *task))block;

/**
 Sets a block to be executed when an HTTP request is attempting to perform a redirection to a different URL, as handled by the `NSURLSessionTaskDelegate` method `URLSession:willPerformHTTPRedirection:newRequest:completionHandler:`.

 @param block A block object to be executed when an HTTP request is attempting to perform a redirection to a different URL. The block returns the request to be made for the redirection, and takes four arguments: the session, the task, the redirection response, and the request corresponding to the redirection response.
 */
- (void)setTaskWillPerformHTTPRedirectionBlock:(nullable NSURLRequest * _Nullable (^)(NSURLSession *session, NSURLSessionTask *task, NSURLResponse *response, NSURLRequest *request))block;

/**
 Sets a block to be executed when a session task has received a request specific authentication challenge, as handled by the `NSURLSessionTaskDelegate` method `URLSession:task:didReceiveChallenge:completionHandler:`.
 
 @param authenticationChallengeHandler A block object to be executed when a session task has received a request specific authentication challenge.
 
 When implementing an authentication challenge handler, you should check the authentication method first (`challenge.protectionSpace.authenticationMethod `) to decide if you want to handle the authentication challenge yourself or if you want AFNetworking to handle it. If you want AFNetworking to handle the authentication challenge, just return `@(NSURLSessionAuthChallengePerformDefaultHandling)`. For example, you certainly want AFNetworking to handle certificate validation (i.e. authentication method == `NSURLAuthenticationMethodServerTrust`) as defined by the security policy. If you want to handle the challenge yourself, you have four options:
 
 1. Return `nil` from the authentication challenge handler. You **MUST** call the completion handler with a disposition and credentials yourself. Use this if you need to present a user interface to let the user enter their credentials.
 2. Return an `NSError` object from the authentication challenge handler. You **MUST NOT** call the completion handler when returning an `NSError `. The returned error will be reported in the completion handler of the task. Use this if you need to abort an authentication challenge with a specific error.
 3. Return an `NSURLCredential` object from the authentication challenge handler. You **MUST NOT** call the completion handler when returning an `NSURLCredential`. The returned credentials will be used to fulfil the challenge. Use this when you can get credentials without presenting a user interface.
 4. Return an `NSNumber` object wrapping an `NSURLSessionAuthChallengeDisposition`. Supported values are `@(NSURLSessionAuthChallengePerformDefaultHandling)`, `@(NSURLSessionAuthChallengeCancelAuthenticationChallenge)` and `@(NSURLSessionAuthChallengeRejectProtectionSpace)`. You **MUST NOT** call the completion handler when returning an `NSNumber`.
 
 If you return anything else from the authentication challenge handler, an exception will be thrown.
 
 For more information about how URL sessions handle the different types of authentication challenges, see [NSURLSession](https://developer.apple.com/reference/foundation/nsurlsession?language=objc) and [URL Session Programming Guide](https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/URLLoadingSystem/URLLoadingSystem.html).
 
 @see -securityPolicy
 */
- (void)setAuthenticationChallengeHandler:(id (^)(NSURLSession *session, NSURLSessionTask *task, NSURLAuthenticationChallenge *challenge, void (^completionHandler)(NSURLSessionAuthChallengeDisposition , NSURLCredential * _Nullable)))authenticationChallengeHandler;

/**
 Sets a block to be executed periodically to track upload progress, as handled by the `NSURLSessionTaskDelegate` method `URLSession:task:didSendBodyData:totalBytesSent:totalBytesExpectedToSend:`.

 @param block A block object to be called when an undetermined number of bytes have been uploaded to the server. This block has no return value and takes five arguments: the session, the task, the number of bytes written since the last time the upload progress block was called, the total bytes written, and the total bytes expected to be written during the request, as initially determined by the length of the HTTP body. This block may be called multiple times, and will execute on the main thread.
 */
- (void)setTaskDidSendBodyDataBlock:(nullable void (^)(NSURLSession *session, NSURLSessionTask *task, int64_t bytesSent, int64_t totalBytesSent, int64_t totalBytesExpectedToSend))block;

/**
 Sets a block to be executed as the last message related to a specific task, as handled by the `NSURLSessionTaskDelegate` method `URLSession:task:didCompleteWithError:`.

 @param block A block object to be executed when a session task is completed. The block has no return value, and takes three arguments: the session, the task, and any error that occurred in the process of executing the task.
 */
- (void)setTaskDidCompleteBlock:(nullable void (^)(NSURLSession *session, NSURLSessionTask *task, NSError * _Nullable error))block;

/**
 Sets a block to be executed when metrics are finalized related to a specific task, as handled by the `NSURLSessionTaskDelegate` method `URLSession:task:didFinishCollectingMetrics:`.

 @param block A block object to be executed when a session task is completed. The block has no return value, and takes three arguments: the session, the task, and any metrics that were collected in the process of executing the task.
 */
#if AF_CAN_INCLUDE_SESSION_TASK_METRICS
- (void)setTaskDidFinishCollectingMetricsBlock:(nullable void (^)(NSURLSession *session, NSURLSessionTask *task, NSURLSessionTaskMetrics * _Nullable metrics))block AF_API_AVAILABLE(ios(10), macosx(10.12), watchos(3), tvos(10));
#endif
///-------------------------------------------
/// @name Setting Data Task Delegate Callbacks
///-------------------------------------------

/**
 Sets a block to be executed when a data task has received a response, as handled by the `NSURLSessionDataDelegate` method `URLSession:dataTask:didReceiveResponse:completionHandler:`.

 @param block A block object to be executed when a data task has received a response. The block returns the disposition of the session response, and takes three arguments: the session, the data task, and the received response.
 */
- (void)setDataTaskDidReceiveResponseBlock:(nullable NSURLSessionResponseDisposition (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSURLResponse *response))block;

/**
 Sets a block to be executed when a data task has become a download task, as handled by the `NSURLSessionDataDelegate` method `URLSession:dataTask:didBecomeDownloadTask:`.

 @param block A block object to be executed when a data task has become a download task. The block has no return value, and takes three arguments: the session, the data task, and the download task it has become.
 */
- (void)setDataTaskDidBecomeDownloadTaskBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSURLSessionDownloadTask *downloadTask))block;

/**
 Sets a block to be executed when a data task receives data, as handled by the `NSURLSessionDataDelegate` method `URLSession:dataTask:didReceiveData:`.

 @param block A block object to be called when an undetermined number of bytes have been downloaded from the server. This block has no return value and takes three arguments: the session, the data task, and the data received. This block may be called multiple times, and will execute on the session manager operation queue.
 */
- (void)setDataTaskDidReceiveDataBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSData *data))block;

/**
 Sets a block to be executed to determine the caching behavior of a data task, as handled by the `NSURLSessionDataDelegate` method `URLSession:dataTask:willCacheResponse:completionHandler:`.

 @param block A block object to be executed to determine the caching behavior of a data task. The block returns the response to cache, and takes three arguments: the session, the data task, and the proposed cached URL response.
 */
- (void)setDataTaskWillCacheResponseBlock:(nullable NSCachedURLResponse * (^)(NSURLSession *session, NSURLSessionDataTask *dataTask, NSCachedURLResponse *proposedResponse))block;

/**
 Sets a block to be executed once all messages enqueued for a session have been delivered, as handled by the `NSURLSessionDelegate` method `URLSessionDidFinishEventsForBackgroundURLSession:`.

 @param block A block object to be executed once all messages enqueued for a session have been delivered. The block has no return value and takes a single argument: the session.
 */
- (void)setDidFinishEventsForBackgroundURLSessionBlock:(nullable void (^)(NSURLSession *session))block AF_API_UNAVAILABLE(macos);

///-----------------------------------------------
/// @name Setting Download Task Delegate Callbacks
///-----------------------------------------------

/**
 Sets a block to be executed when a download task has completed a download, as handled by the `NSURLSessionDownloadDelegate` method `URLSession:downloadTask:didFinishDownloadingToURL:`.

 @param block A block object to be executed when a download task has completed. The block returns the URL the download should be moved to, and takes three arguments: the session, the download task, and the temporary location of the downloaded file. If the file manager encounters an error while attempting to move the temporary file to the destination, an `AFURLSessionDownloadTaskDidFailToMoveFileNotification` will be posted, with the download task as its object, and the user info of the error.
 */
- (void)setDownloadTaskDidFinishDownloadingBlock:(nullable NSURL * _Nullable  (^)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, NSURL *location))block;

/**
 Sets a block to be executed periodically to track download progress, as handled by the `NSURLSessionDownloadDelegate` method `URLSession:downloadTask:didWriteData:totalBytesWritten:totalBytesExpectedToWrite:`.

 @param block A block object to be called when an undetermined number of bytes have been downloaded from the server. This block has no return value and takes five arguments: the session, the download task, the number of bytes read since the last time the download progress block was called, the total bytes read, and the total bytes expected to be read during the request, as initially determined by the expected content size of the `NSHTTPURLResponse` object. This block may be called multiple times, and will execute on the session manager operation queue.
 */
- (void)setDownloadTaskDidWriteDataBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, int64_t bytesWritten, int64_t totalBytesWritten, int64_t totalBytesExpectedToWrite))block;

/**
 Sets a block to be executed when a download task has been resumed, as handled by the `NSURLSessionDownloadDelegate` method `URLSession:downloadTask:didResumeAtOffset:expectedTotalBytes:`.

 @param block A block object to be executed when a download task has been resumed. The block has no return value and takes four arguments: the session, the download task, the file offset of the resumed download, and the total number of bytes expected to be downloaded.
 */
- (void)setDownloadTaskDidResumeBlock:(nullable void (^)(NSURLSession *session, NSURLSessionDownloadTask *downloadTask, int64_t fileOffset, int64_t expectedTotalBytes))block;

@interface AFHTTPSessionManager : AFURLSessionManager <NSSecureCoding, NSCopying>
@property (readonly, nonatomic, strong, nullable) NSURL *baseURL;
/**
 Requests created with `requestWithMethod:URLString:parameters:` & `multipartFormRequestWithMethod:URLString:parameters:constructingBodyWithBlock:` are constructed with a set of default headers using a parameter serialization specified by this property. By default, this is set to an instance of `AFHTTPRequestSerializer`, which serializes query string parameters for `GET`, `HEAD`, and `DELETE` requests, or otherwise URL-form-encodes HTTP message bodies.

 @warning `requestSerializer` must not be `nil`.
 */
@property (nonatomic, strong) AFHTTPRequestSerializer <AFURLRequestSerialization> * requestSerializer;

/**
 Responses sent from the server in data tasks created with `dataTaskWithRequest:success:failure:` and run using the `GET` / `POST` / et al. convenience methods are automatically validated and serialized by the response serializer. By default, this property is set to an instance of `AFJSONResponseSerializer`.

 @warning `responseSerializer` must not be `nil`.
 */
@property (nonatomic, strong) AFHTTPResponseSerializer <AFURLResponseSerialization> * responseSerializer;

/**
 The security policy used by created session to evaluate server trust for secure connections. `AFURLSessionManager` uses the `defaultPolicy` unless otherwise specified. A security policy configured with `AFSSLPinningModePublicKey` or `AFSSLPinningModeCertificate` can only be applied on a session manager initialized with a secure base URL (i.e. https). Applying a security policy with pinning enabled on an insecure session manager throws an `Invalid Security Policy` exception.
 */
@property (nonatomic, strong) AFSecurityPolicy *securityPolicy;
  
@end

/**
 The `AFURLRequestSerialization` protocol is adopted by an object that encodes parameters for a specified HTTP requests. Request serializers may encode parameters as query strings, HTTP bodies, setting the appropriate HTTP header fields as necessary.

 For example, a JSON request serializer may set the HTTP body of the request to a JSON representation, and set the `Content-Type` HTTP header field value to `application/json`.
 */
@protocol AFURLRequestSerialization <NSObject, NSSecureCoding, NSCopying>

/**
 Returns a request with the specified parameters encoded into a copy of the original request.

 @param request The original request.
 @param parameters The parameters to be encoded.
 @param error The error that occurred while attempting to encode the request parameters.

 @return A serialized request.
 */
- (nullable NSURLRequest *)requestBySerializingRequest:(NSURLRequest *)request
                               withParameters:(nullable id)parameters
                                        error:(NSError * _Nullable __autoreleasing *)error NS_SWIFT_NOTHROW;

@end

/**
 The `AFMultipartFormData` protocol defines the methods supported by the parameter in the block argument of `AFHTTPRequestSerializer -multipartFormRequestWithMethod:URLString:parameters:constructingBodyWithBlock:error:`.
 */
@protocol AFMultipartFormData

/**
 Appends the HTTP header `Content-Disposition: file; filename=#{generated filename}; name=#{name}"` and `Content-Type: #{generated mimeType}`, followed by the encoded file data and the multipart form boundary.

 The filename and MIME type for this data in the form will be automatically generated, using the last path component of the `fileURL` and system associated MIME type for the `fileURL` extension, respectively.

 @param fileURL The URL corresponding to the file whose content will be appended to the form. This parameter must not be `nil`.
 @param name The name to be associated with the specified data. This parameter must not be `nil`.
 @param error If an error occurs, upon return contains an `NSError` object that describes the problem.

 @return `YES` if the file data was successfully appended, otherwise `NO`.
 */
- (BOOL)appendPartWithFileURL:(NSURL *)fileURL
                         name:(NSString *)name
                        error:(NSError * _Nullable __autoreleasing *)error;

/**
 Appends the HTTP header `Content-Disposition: file; filename=#{filename}; name=#{name}"` and `Content-Type: #{mimeType}`, followed by the encoded file data and the multipart form boundary.

 @param fileURL The URL corresponding to the file whose content will be appended to the form. This parameter must not be `nil`.
 @param name The name to be associated with the specified data. This parameter must not be `nil`.
 @param fileName The file name to be used in the `Content-Disposition` header. This parameter must not be `nil`.
 @param mimeType The declared MIME type of the file data. This parameter must not be `nil`.
 @param error If an error occurs, upon return contains an `NSError` object that describes the problem.

 @return `YES` if the file data was successfully appended otherwise `NO`.
 */
- (BOOL)appendPartWithFileURL:(NSURL *)fileURL
                         name:(NSString *)name
                     fileName:(NSString *)fileName
                     mimeType:(NSString *)mimeType
                        error:(NSError * _Nullable __autoreleasing *)error;

/**
 Appends the HTTP header `Content-Disposition: file; filename=#{filename}; name=#{name}"` and `Content-Type: #{mimeType}`, followed by the data from the input stream and the multipart form boundary.

 @param inputStream The input stream to be appended to the form data
 @param name The name to be associated with the specified input stream. This parameter must not be `nil`.
 @param fileName The filename to be associated with the specified input stream. This parameter must not be `nil`.
 @param length The length of the specified input stream in bytes.
 @param mimeType The MIME type of the specified data. (For example, the MIME type for a JPEG image is image/jpeg.) For a list of valid MIME types, see http://www.iana.org/assignments/media-types/. This parameter must not be `nil`.
 */
- (void)appendPartWithInputStream:(nullable NSInputStream *)inputStream
                             name:(NSString *)name
                         fileName:(NSString *)fileName
                           length:(int64_t)length
                         mimeType:(NSString *)mimeType;

/**
 Appends the HTTP header `Content-Disposition: file; filename=#{filename}; name=#{name}"` and `Content-Type: #{mimeType}`, followed by the encoded file data and the multipart form boundary.

 @param data The data to be encoded and appended to the form data.
 @param name The name to be associated with the specified data. This parameter must not be `nil`.
 @param fileName The filename to be associated with the specified data. This parameter must not be `nil`.
 @param mimeType The MIME type of the specified data. (For example, the MIME type for a JPEG image is image/jpeg.) For a list of valid MIME types, see http://www.iana.org/assignments/media-types/. This parameter must not be `nil`.
 */
- (void)appendPartWithFileData:(NSData *)data
                          name:(NSString *)name
                      fileName:(NSString *)fileName
                      mimeType:(NSString *)mimeType;

/**
 Appends the HTTP headers `Content-Disposition: form-data; name=#{name}"`, followed by the encoded data and the multipart form boundary.

 @param data The data to be encoded and appended to the form data.
 @param name The name to be associated with the specified data. This parameter must not be `nil`.
 */

- (void)appendPartWithFormData:(NSData *)data
                          name:(NSString *)name;


/**
 Appends HTTP headers, followed by the encoded data and the multipart form boundary.

 @param headers The HTTP headers to be appended to the form data.
 @param body The data to be encoded and appended to the form data. This parameter must not be `nil`.
 */
- (void)appendPartWithHeaders:(nullable NSDictionary <NSString *, NSString *> *)headers
                         body:(NSData *)body;

/**
 Throttles request bandwidth by limiting the packet size and adding a delay for each chunk read from the upload stream.

 When uploading over a 3G or EDGE connection, requests may fail with "request body stream exhausted". Setting a maximum packet size and delay according to the recommended values (`kAFUploadStream3GSuggestedPacketSize` and `kAFUploadStream3GSuggestedDelay`) lowers the risk of the input stream exceeding its allocated bandwidth. Unfortunately, there is no definite way to distinguish between a 3G, EDGE, or LTE connection over `NSURLConnection`. As such, it is not recommended that you throttle bandwidth based solely on network reachability. Instead, you should consider checking for the "request body stream exhausted" in a failure block, and then retrying the request with throttled bandwidth.

 @param numberOfBytes Maximum packet size, in number of bytes. The default packet size for an input stream is 16kb.
 @param delay Duration of delay each time a packet is read. By default, no delay is set.
 */
- (void)throttleBandwidthWithPacketSize:(NSUInteger)numberOfBytes
                                  delay:(NSTimeInterval)delay;

@end

@property (nonatomic, assign) NSStringEncoding stringEncoding;
@property (nonatomic, strong) NSDictionary *headers;
@property (nonatomic, copy) NSString *boundary;
@property (nonatomic, strong) id body;
@property (nonatomic, assign) NSUInteger bodyContentLength;
@property (nonatomic, strong) NSInputStream *inputStream;
@property (nonatomic, assign) BOOL hasInitialBoundary;
@property (nonatomic, assign) BOOL hasFinalBoundary;
@property (readonly, nonatomic, assign, getter = hasBytesAvailable) BOOL bytesAvailable;
@property (readonly, nonatomic, assign) NSUInteger contentLength;

- (NSInteger)read:(uint8_t *)buffer
        maxLength:(NSUInteger)length;

typedef enum {
    AFEncapsulationBoundaryPhase = 1,
    AFHeaderPhase                = 2,
    AFBodyPhase                  = 3,
    AFFinalBoundaryPhase         = 4,
} AFHTTPBodyPartReadPhase;

@interface AFHTTPBodyPart () <NSCopying> {
    AFHTTPBodyPartReadPhase _phase;
    NSInputStream *_inputStream;
    unsigned long long _phaseReadOffset;
}

- (BOOL)transitionToNextPhase;
- (NSInteger)readData:(NSData *)data
           intoBuffer:(uint8_t *)buffer
            maxLength:(NSUInteger)length;
@end

@implementation AFHTTPBodyPart

- (instancetype)init {
    self = [super init];
    if (!self) {
        return nil;
    }

    [self transitionToNextPhase];

    return self;
}

- (void)dealloc {
    if (_inputStream) {
        [_inputStream close];
        _inputStream = nil;
    }
}

// inputStream
- (NSInputStream *)inputStream {
    if (!_inputStream) {
        if ([self.body isKindOfClass:[NSData class]]) {
            _inputStream = [NSInputStream inputStreamWithData:self.body];
        } else if ([self.body isKindOfClass:[NSURL class]]) {
            _inputStream = [NSInputStream inputStreamWithURL:self.body];
        } else if ([self.body isKindOfClass:[NSInputStream class]]) {
            _inputStream = self.body;
        } else {
            _inputStream = [NSInputStream inputStreamWithData:[NSData data]];
        }
    }

    return _inputStream;
}

- (NSString *)stringForHeaders {
    NSMutableString *headerString = [NSMutableString string];
    for (NSString *field in [self.headers allKeys]) {
        [headerString appendString:[NSString stringWithFormat:@"%@: %@%@", field, [self.headers valueForKey:field], kAFMultipartFormCRLF]];
    }
    [headerString appendString:kAFMultipartFormCRLF];

    return [NSString stringWithString:headerString];
}

- (unsigned long long)contentLength {
    unsigned long long length = 0;

    NSData *encapsulationBoundaryData = [([self hasInitialBoundary] ? AFMultipartFormInitialBoundary(self.boundary) : AFMultipartFormEncapsulationBoundary(self.boundary)) dataUsingEncoding:self.stringEncoding];
    length += [encapsulationBoundaryData length];

    NSData *headersData = [[self stringForHeaders] dataUsingEncoding:self.stringEncoding];
    length += [headersData length];

    length += _bodyContentLength;

    NSData *closingBoundaryData = ([self hasFinalBoundary] ? [AFMultipartFormFinalBoundary(self.boundary) dataUsingEncoding:self.stringEncoding] : [NSData data]);
    length += [closingBoundaryData length];

    return length;
}

- (BOOL)hasBytesAvailable {
    // Allows `read:maxLength:` to be called again if `AFMultipartFormFinalBoundary` doesn't fit into the available buffer
    if (_phase == AFFinalBoundaryPhase) {
        return YES;
    }

    switch (self.inputStream.streamStatus) {
        case NSStreamStatusNotOpen:
        case NSStreamStatusOpening:
        case NSStreamStatusOpen:
        case NSStreamStatusReading:
        case NSStreamStatusWriting:
            return YES;
        case NSStreamStatusAtEnd:
        case NSStreamStatusClosed:
        case NSStreamStatusError:
        default:
            return NO;
    }
}

- (NSInteger)read:(uint8_t *)buffer
        maxLength:(NSUInteger)length
{
    NSInteger totalNumberOfBytesRead = 0;

    if (_phase == AFEncapsulationBoundaryPhase) {
        NSData *encapsulationBoundaryData = [([self hasInitialBoundary] ? AFMultipartFormInitialBoundary(self.boundary) : AFMultipartFormEncapsulationBoundary(self.boundary)) dataUsingEncoding:self.stringEncoding];
        totalNumberOfBytesRead += [self readData:encapsulationBoundaryData intoBuffer:&buffer[totalNumberOfBytesRead] maxLength:(length - (NSUInteger)totalNumberOfBytesRead)];
    }

    if (_phase == AFHeaderPhase) {
        NSData *headersData = [[self stringForHeaders] dataUsingEncoding:self.stringEncoding];
        totalNumberOfBytesRead += [self readData:headersData intoBuffer:&buffer[totalNumberOfBytesRead] maxLength:(length - (NSUInteger)totalNumberOfBytesRead)];
    }

    if (_phase == AFBodyPhase) {
        NSInteger numberOfBytesRead = 0;

        numberOfBytesRead = [self.inputStream read:&buffer[totalNumberOfBytesRead] maxLength:(length - (NSUInteger)totalNumberOfBytesRead)];
        if (numberOfBytesRead == -1) {
            return -1;
        } else {
            totalNumberOfBytesRead += numberOfBytesRead;

            if ([self.inputStream streamStatus] >= NSStreamStatusAtEnd) {
                [self transitionToNextPhase];
            }
        }
    }

    if (_phase == AFFinalBoundaryPhase) {
        NSData *closingBoundaryData = ([self hasFinalBoundary] ? [AFMultipartFormFinalBoundary(self.boundary) dataUsingEncoding:self.stringEncoding] : [NSData data]);
        totalNumberOfBytesRead += [self readData:closingBoundaryData intoBuffer:&buffer[totalNumberOfBytesRead] maxLength:(length - (NSUInteger)totalNumberOfBytesRead)];
    }

    return totalNumberOfBytesRead;
}

- (NSInteger)readData:(NSData *)data
           intoBuffer:(uint8_t *)buffer
            maxLength:(NSUInteger)length
{
    NSRange range = NSMakeRange((NSUInteger)_phaseReadOffset, MIN([data length] - ((NSUInteger)_phaseReadOffset), length));
    [data getBytes:buffer range:range];

    _phaseReadOffset += range.length;

    if (((NSUInteger)_phaseReadOffset) >= [data length]) {
        [self transitionToNextPhase];
    }

    return (NSInteger)range.length;
}

- (BOOL)transitionToNextPhase {
    if (![[NSThread currentThread] isMainThread]) {
        dispatch_sync(dispatch_get_main_queue(), ^{
            [self transitionToNextPhase];
        });
        return YES;
    }

    switch (_phase) {
        case AFEncapsulationBoundaryPhase:
            _phase = AFHeaderPhase;
            break;
        case AFHeaderPhase:
            [self.inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
            [self.inputStream open];
            _phase = AFBodyPhase;
            break;
        case AFBodyPhase:
            [self.inputStream close];
            _phase = AFFinalBoundaryPhase;
            break;
        case AFFinalBoundaryPhase:
        default:
            _phase = AFEncapsulationBoundaryPhase;
            break;
    }
    _phaseReadOffset = 0;

    return YES;
}

#pragma mark - NSCopying

- (instancetype)copyWithZone:(NSZone *)zone {
    AFHTTPBodyPart *bodyPart = [[[self class] allocWithZone:zone] init];

    bodyPart.stringEncoding = self.stringEncoding;
    bodyPart.headers = self.headers;
    bodyPart.bodyContentLength = self.bodyContentLength;
    bodyPart.body = self.body;
    bodyPart.boundary = self.boundary;

    return bodyPart;
}

@end

@interface AFMultipartBodyStream : NSInputStream <NSStreamDelegate>
@property (nonatomic, assign) NSUInteger numberOfBytesInPacket;
@property (nonatomic, assign) NSTimeInterval delay;
@property (nonatomic, strong) NSInputStream *inputStream;
@property (readonly, nonatomic, assign) unsigned long long contentLength;
@property (readonly, nonatomic, assign, getter = isEmpty) BOOL empty;

- (instancetype)initWithStringEncoding:(NSStringEncoding)encoding;
- (void)setInitialAndFinalBoundaries;
- (void)appendHTTPBodyPart:(AFHTTPBodyPart *)bodyPart;
@end

@implementation AFMultipartBodyStream
#if (defined(__IPHONE_OS_VERSION_MAX_ALLOWED) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 80000) || (defined(__MAC_OS_X_VERSION_MAX_ALLOWED) && __MAC_OS_X_VERSION_MAX_ALLOWED >= 1100)
@synthesize delegate;
#endif
@synthesize streamStatus;
@synthesize streamError;

- (instancetype)initWithStringEncoding:(NSStringEncoding)encoding {
    self = [super init];
    if (!self) {
        return nil;
    }

    self.stringEncoding = encoding;
    self.HTTPBodyParts = [NSMutableArray array];
    self.numberOfBytesInPacket = NSIntegerMax;

    return self;
}

- (void)setInitialAndFinalBoundaries {
    if ([self.HTTPBodyParts count] > 0) {
        for (AFHTTPBodyPart *bodyPart in self.HTTPBodyParts) {
            bodyPart.hasInitialBoundary = NO;
            bodyPart.hasFinalBoundary = NO;
        }

        [[self.HTTPBodyParts firstObject] setHasInitialBoundary:YES];
        [[self.HTTPBodyParts lastObject] setHasFinalBoundary:YES];
    }
}

- (void)appendHTTPBodyPart:(AFHTTPBodyPart *)bodyPart {
    [self.HTTPBodyParts addObject:bodyPart];
}

- (BOOL)isEmpty {
    return [self.HTTPBodyParts count] == 0;
}

#pragma mark - NSInputStream

- (NSInteger)read:(uint8_t *)buffer
        maxLength:(NSUInteger)length
{
    if ([self streamStatus] == NSStreamStatusClosed) {
        return 0;
    }

    NSInteger totalNumberOfBytesRead = 0;

    while ((NSUInteger)totalNumberOfBytesRead < MIN(length, self.numberOfBytesInPacket)) {
        if (!self.currentHTTPBodyPart || ![self.currentHTTPBodyPart hasBytesAvailable]) {
            if (!(self.currentHTTPBodyPart = [self.HTTPBodyPartEnumerator nextObject])) {
                break;
            }
        } else {
            NSUInteger maxLength = MIN(length, self.numberOfBytesInPacket) - (NSUInteger)totalNumberOfBytesRead;
            NSInteger numberOfBytesRead = [self.currentHTTPBodyPart read:&buffer[totalNumberOfBytesRead] maxLength:maxLength];
            if (numberOfBytesRead == -1) {
                self.streamError = self.currentHTTPBodyPart.inputStream.streamError;
                break;
            } else {
                totalNumberOfBytesRead += numberOfBytesRead;

                if (self.delay > 0.0f) {
                    [NSThread sleepForTimeInterval:self.delay];
                }
            }
        }
    }

    return totalNumberOfBytesRead;
}

- (BOOL)getBuffer:(__unused uint8_t **)buffer
           length:(__unused NSUInteger *)len
{
    return NO;
}

- (BOOL)hasBytesAvailable {
    return [self streamStatus] == NSStreamStatusOpen;
}

#pragma mark - NSStream

- (void)open {
    if (self.streamStatus == NSStreamStatusOpen) {
        return;
    }

    self.streamStatus = NSStreamStatusOpen;

    [self setInitialAndFinalBoundaries];
    self.HTTPBodyPartEnumerator = [self.HTTPBodyParts objectEnumerator];
}

- (void)close {
    self.streamStatus = NSStreamStatusClosed;
}

- (id)propertyForKey:(__unused NSString *)key {
    return nil;
}

- (BOOL)setProperty:(__unused id)property
             forKey:(__unused NSString *)key
{
    return NO;
}

- (void)scheduleInRunLoop:(__unused NSRunLoop *)aRunLoop
                  forMode:(__unused NSString *)mode
{}

- (void)removeFromRunLoop:(__unused NSRunLoop *)aRunLoop
                  forMode:(__unused NSString *)mode
{}

- (unsigned long long)contentLength {
    unsigned long long length = 0;
    for (AFHTTPBodyPart *bodyPart in self.HTTPBodyParts) {
        length += [bodyPart contentLength];
    }

    return length;
}

#pragma mark - Undocumented CFReadStream Bridged Methods

- (void)_scheduleInCFRunLoop:(__unused CFRunLoopRef)aRunLoop
                     forMode:(__unused CFStringRef)aMode
{}

- (void)_unscheduleFromCFRunLoop:(__unused CFRunLoopRef)aRunLoop
                         forMode:(__unused CFStringRef)aMode
{}

- (BOOL)_setCFClientFlags:(__unused CFOptionFlags)inFlags
                 callback:(__unused CFReadStreamClientCallBack)inCallback
                  context:(__unused CFStreamClientContext *)inContext {
    return NO;
}

#pragma mark - NSCopying

- (instancetype)copyWithZone:(NSZone *)zone {
    AFMultipartBodyStream *bodyStreamCopy = [[[self class] allocWithZone:zone] initWithStringEncoding:self.stringEncoding];

    for (AFHTTPBodyPart *bodyPart in self.HTTPBodyParts) {
        [bodyStreamCopy appendHTTPBodyPart:[bodyPart copy]];
    }

    [bodyStreamCopy setInitialAndFinalBoundaries];

    return bodyStreamCopy;
}

@end

static NSString * AFCreateMultipartFormBoundary() {
    return [NSString stringWithFormat:@"Boundary+%08X%08X", arc4random(), arc4random()];
}

static NSString * const kAFMultipartFormCRLF = @"\r\n";

static inline NSString * AFMultipartFormInitialBoundary(NSString *boundary) {
    return [NSString stringWithFormat:@"--%@%@", boundary, kAFMultipartFormCRLF];
}

static inline NSString * AFMultipartFormEncapsulationBoundary(NSString *boundary) {
    return [NSString stringWithFormat:@"%@--%@%@", kAFMultipartFormCRLF, boundary, kAFMultipartFormCRLF];
}

static inline NSString * AFMultipartFormFinalBoundary(NSString *boundary) {
    return [NSString stringWithFormat:@"%@--%@--%@", kAFMultipartFormCRLF, boundary, kAFMultipartFormCRLF];
}

static inline NSString * AFContentTypeForPathExtension(NSString *extension) {
    NSString *UTI = (__bridge_transfer NSString *)UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, (__bridge CFStringRef)extension, NULL);
    NSString *contentType = (__bridge_transfer NSString *)UTTypeCopyPreferredTagWithClass((__bridge CFStringRef)UTI, kUTTagClassMIMEType);
    if (!contentType) {
        return @"application/octet-stream";
    } else {
        return contentType;
    }
}

@interface AFStreamingMultipartFormData : NSObject <AFMultipartFormData>
- (instancetype)initWithURLRequest:(NSMutableURLRequest *)urlRequest
                    stringEncoding:(NSStringEncoding)encoding;

- (NSMutableURLRequest *)requestByFinalizingMultipartFormData;
@end
  
@interface AFStreamingMultipartFormData ()
@property (readwrite, nonatomic, copy) NSMutableURLRequest *request;
@property (readwrite, nonatomic, assign) NSStringEncoding stringEncoding;
@property (readwrite, nonatomic, copy) NSString *boundary;
@property (readwrite, nonatomic, strong) AFMultipartBodyStream *bodyStream;
@end  

@implementation AFStreamingMultipartFormData

- (instancetype)initWithURLRequest:(NSMutableURLRequest *)urlRequest
                    stringEncoding:(NSStringEncoding)encoding
{
    self = [super init];
    if (!self) {
        return nil;
    }

    self.request = urlRequest;
    self.stringEncoding = encoding;
    self.boundary = AFCreateMultipartFormBoundary();
    self.bodyStream = [[AFMultipartBodyStream alloc] initWithStringEncoding:encoding];

    return self;
}

- (void)setRequest:(NSMutableURLRequest *)request
{
    _request = [request mutableCopy];
}

- (BOOL)appendPartWithFileURL:(NSURL *)fileURL
                         name:(NSString *)name
                        error:(NSError * __autoreleasing *)error
{
    NSParameterAssert(fileURL);
    NSParameterAssert(name);

    NSString *fileName = [fileURL lastPathComponent];
    NSString *mimeType = AFContentTypeForPathExtension([fileURL pathExtension]);

    return [self appendPartWithFileURL:fileURL name:name fileName:fileName mimeType:mimeType error:error];
}

- (BOOL)appendPartWithFileURL:(NSURL *)fileURL
                         name:(NSString *)name
                     fileName:(NSString *)fileName
                     mimeType:(NSString *)mimeType
                        error:(NSError * __autoreleasing *)error
{
    NSParameterAssert(fileURL);
    NSParameterAssert(name);
    NSParameterAssert(fileName);
    NSParameterAssert(mimeType);

    if (![fileURL isFileURL]) {
        NSDictionary *userInfo = @{NSLocalizedFailureReasonErrorKey: NSLocalizedStringFromTable(@"Expected URL to be a file URL", @"AFNetworking", nil)};
        if (error) {
            *error = [[NSError alloc] initWithDomain:AFURLRequestSerializationErrorDomain code:NSURLErrorBadURL userInfo:userInfo];
        }

        return NO;
    } else if ([fileURL checkResourceIsReachableAndReturnError:error] == NO) {
        NSDictionary *userInfo = @{NSLocalizedFailureReasonErrorKey: NSLocalizedStringFromTable(@"File URL not reachable.", @"AFNetworking", nil)};
        if (error) {
            *error = [[NSError alloc] initWithDomain:AFURLRequestSerializationErrorDomain code:NSURLErrorBadURL userInfo:userInfo];
        }

        return NO;
    }

    NSDictionary *fileAttributes = [[NSFileManager defaultManager] attributesOfItemAtPath:[fileURL path] error:error];
    if (!fileAttributes) {
        return NO;
    }

    NSMutableDictionary *mutableHeaders = [NSMutableDictionary dictionary];
    [mutableHeaders setValue:[NSString stringWithFormat:@"form-data; name=\"%@\"; filename=\"%@\"", name, fileName] forKey:@"Content-Disposition"];
    [mutableHeaders setValue:mimeType forKey:@"Content-Type"];

// 将URL组装成bodyPart
    AFHTTPBodyPart *bodyPart = [[AFHTTPBodyPart alloc] init];
    bodyPart.stringEncoding = self.stringEncoding;
    bodyPart.headers = mutableHeaders;
    bodyPart.boundary = self.boundary;
    bodyPart.body = fileURL;
    bodyPart.bodyContentLength = [fileAttributes[NSFileSize] unsignedLongLongValue];
    [self.bodyStream appendHTTPBodyPart:bodyPart];

    return YES;
}

- (void)appendPartWithInputStream:(NSInputStream *)inputStream
                             name:(NSString *)name
                         fileName:(NSString *)fileName
                           length:(int64_t)length
                         mimeType:(NSString *)mimeType
{
    NSParameterAssert(name);
    NSParameterAssert(fileName);
    NSParameterAssert(mimeType);

    NSMutableDictionary *mutableHeaders = [NSMutableDictionary dictionary];
    [mutableHeaders setValue:[NSString stringWithFormat:@"form-data; name=\"%@\"; filename=\"%@\"", name, fileName] forKey:@"Content-Disposition"];
    [mutableHeaders setValue:mimeType forKey:@"Content-Type"];

 // 将inputStream组装成bodyPart                         
    AFHTTPBodyPart *bodyPart = [[AFHTTPBodyPart alloc] init];
    bodyPart.stringEncoding = self.stringEncoding;
    bodyPart.headers = mutableHeaders;
    bodyPart.boundary = self.boundary;
    bodyPart.body = inputStream;

    bodyPart.bodyContentLength = (unsigned long long)length;

    [self.bodyStream appendHTTPBodyPart:bodyPart];
}

- (void)appendPartWithFileData:(NSData *)data
                          name:(NSString *)name
                      fileName:(NSString *)fileName
                      mimeType:(NSString *)mimeType
{
    NSParameterAssert(name);
    NSParameterAssert(fileName);
    NSParameterAssert(mimeType);

    NSMutableDictionary *mutableHeaders = [NSMutableDictionary dictionary];
    [mutableHeaders setValue:[NSString stringWithFormat:@"form-data; name=\"%@\"; filename=\"%@\"", name, fileName] forKey:@"Content-Disposition"];
    [mutableHeaders setValue:mimeType forKey:@"Content-Type"];
// 将data组装成bodyPart
    [self appendPartWithHeaders:mutableHeaders body:data];
}

- (void)appendPartWithFormData:(NSData *)data
                          name:(NSString *)name
{
    NSParameterAssert(name);

    NSMutableDictionary *mutableHeaders = [NSMutableDictionary dictionary];
    [mutableHeaders setValue:[NSString stringWithFormat:@"form-data; name=\"%@\"", name] forKey:@"Content-Disposition"];

    [self appendPartWithHeaders:mutableHeaders body:data];
}

- (void)appendPartWithHeaders:(NSDictionary *)headers
                         body:(NSData *)body
{
    NSParameterAssert(body);

// 将data组装成bodyPart                           
    AFHTTPBodyPart *bodyPart = [[AFHTTPBodyPart alloc] init];
    bodyPart.stringEncoding = self.stringEncoding;
    bodyPart.headers = headers;
    bodyPart.boundary = self.boundary;
    bodyPart.bodyContentLength = [body length];
    bodyPart.body = body;

    [self.bodyStream appendHTTPBodyPart:bodyPart];
}

- (void)throttleBandwidthWithPacketSize:(NSUInteger)numberOfBytes
                                  delay:(NSTimeInterval)delay
{
    self.bodyStream.numberOfBytesInPacket = numberOfBytes;
    self.bodyStream.delay = delay;
}

// 将multipartFormData组装成request
- (NSMutableURLRequest *)requestByFinalizingMultipartFormData {
    if ([self.bodyStream isEmpty]) {
        return self.request;
    }

    // Reset the initial and final boundaries to ensure correct Content-Length
    [self.bodyStream setInitialAndFinalBoundaries];
    [self.request setHTTPBodyStream:self.bodyStream];

    [self.request setValue:[NSString stringWithFormat:@"multipart/form-data; boundary=%@", self.boundary] forHTTPHeaderField:@"Content-Type"];
    [self.request setValue:[NSString stringWithFormat:@"%llu", [self.bodyStream contentLength]] forHTTPHeaderField:@"Content-Length"];

    return self.request;
}

@end

/*!
 @enum NSURLRequestNetworkServiceType
 
 @discussion The NSURLRequestNetworkServiceType enum defines constants that
 can be used to specify the service type to associate with this request.  The
 service type is used to provide the networking layers a hint of the purpose 
 of the request.
 
 @constant NSURLNetworkServiceTypeDefault Is the default value for an NSURLRequest
 when created.  This value should be left unchanged for the vast majority of requests.
 
 @constant NSURLNetworkServiceTypeVoIP Specifies that the request is for voice over IP
 control traffic.
 
 @constant NSURLNetworkServiceTypeVideo Specifies that the request is for video
 traffic.

 @constant NSURLNetworkServiceTypeBackground Specifies that the request is for background
 traffic (such as a file download).

 @constant NSURLNetworkServiceTypeVoice Specifies that the request is for voice data.

 @constant NSURLNetworkServiceTypeResponsiveData Specifies that the request is for responsive (time sensitive) data.

 @constant NSURLNetworkServiceTypeAVStreaming Specifies that the request is streaming audio/video data.

 @constant NSURLNetworkServiceTypeResponsiveAV Specifies that the request is for responsive (time sensitive) audio/video data.

 @constant NSURLNetworkServiceTypeCallSignaling Specifies that the request is for call signaling.
*/
typedef NS_ENUM(NSUInteger, NSURLRequestNetworkServiceType)
{
    NSURLNetworkServiceTypeDefault = 0,	// Standard internet traffic
    NSURLNetworkServiceTypeVoIP API_DEPRECATED("Use PushKit for VoIP control purposes", macos(10.7,10.15), ios(4.0,13.0), watchos(2.0,6.0), tvos(9.0,13.0)) = 1,	// Voice over IP control traffic
    NSURLNetworkServiceTypeVideo = 2,	// Video traffic
    NSURLNetworkServiceTypeBackground = 3, // Background traffic
    NSURLNetworkServiceTypeVoice = 4,	   // Voice data
    NSURLNetworkServiceTypeResponsiveData = 6, // Responsive data
    NSURLNetworkServiceTypeAVStreaming API_AVAILABLE(macosx(10.9), ios(7.0), watchos(2.0), tvos(9.0)) = 8 , // Multimedia Audio/Video Streaming
    NSURLNetworkServiceTypeResponsiveAV API_AVAILABLE(macosx(10.9), ios(7.0), watchos(2.0), tvos(9.0)) = 9, // Responsive Multimedia Audio/Video
    NSURLNetworkServiceTypeCallSignaling API_AVAILABLE(macosx(10.12), ios(10.0), watchos(3.0), tvos(10.0)) = 11, // Call Signaling
};

/**
 `AFHTTPRequestSerializer` conforms to the `AFURLRequestSerialization` & `AFURLResponseSerialization` protocols, offering a concrete base implementation of query string / URL form-encoded parameter serialization and default request headers, as well as response status code and content type validation.

 Any request or response serializer dealing with HTTP is encouraged to subclass `AFHTTPRequestSerializer` in order to ensure consistent default behavior.
 */
@interface AFHTTPRequestSerializer : NSObject <AFURLRequestSerialization>

/**
 The string encoding used to serialize parameters. `NSUTF8StringEncoding` by default.
 */
@property (nonatomic, assign) NSStringEncoding stringEncoding;

/**
 Whether created requests can use the device’s cellular radio (if present). `YES` by default.

 @see NSMutableURLRequest -setAllowsCellularAccess:
 */
@property (nonatomic, assign) BOOL allowsCellularAccess;

/**
 The cache policy of created requests. `NSURLRequestUseProtocolCachePolicy` by default.

 @see NSMutableURLRequest -setCachePolicy:
 */
@property (nonatomic, assign) NSURLRequestCachePolicy cachePolicy;

/**
 Whether created requests should use the default cookie handling. `YES` by default.

 @see NSMutableURLRequest -setHTTPShouldHandleCookies:
 */
@property (nonatomic, assign) BOOL HTTPShouldHandleCookies;

/**
 Whether created requests can continue transmitting data before receiving a response from an earlier transmission. `NO` by default

 @see NSMutableURLRequest -setHTTPShouldUsePipelining:
 */
@property (nonatomic, assign) BOOL HTTPShouldUsePipelining;

/**
 The network service type for created requests. `NSURLNetworkServiceTypeDefault` by default.

 @see NSMutableURLRequest -setNetworkServiceType:
 */
@property (nonatomic, assign) NSURLRequestNetworkServiceType networkServiceType;

/**
 The timeout interval, in seconds, for created requests. The default timeout interval is 60 seconds.

 @see NSMutableURLRequest -setTimeoutInterval:
 */
@property (nonatomic, assign) NSTimeInterval timeoutInterval;

///---------------------------------------
/// @name Configuring HTTP Request Headers
///---------------------------------------

/**
 Default HTTP header field values to be applied to serialized requests. By default, these include the following:

 - `Accept-Language` with the contents of `NSLocale +preferredLanguages`
 - `User-Agent` with the contents of various bundle identifiers and OS designations

 @discussion To add or remove default request headers, use `setValue:forHTTPHeaderField:`.
 */
@property (readonly, nonatomic, strong) NSDictionary <NSString *, NSString *> *HTTPRequestHeaders;

/**
 Sets the value for the HTTP headers set in request objects made by the HTTP client. If `nil`, removes the existing value for that header.

 @param field The HTTP header to set a default value for
 @param value The value set as default for the specified header, or `nil`
 */
- (void)setValue:(nullable NSString *)value
forHTTPHeaderField:(NSString *)field;

/**
 Returns the value for the HTTP headers set in the request serializer.

 @param field The HTTP header to retrieve the default value for

 @return The value set as default for the specified header, or `nil`
 */
- (nullable NSString *)valueForHTTPHeaderField:(NSString *)field;

/**
 Sets the "Authorization" HTTP header set in request objects made by the HTTP client to a basic authentication value with Base64-encoded username and password. This overwrites any existing value for this header.

 @param username The HTTP basic auth username
 @param password The HTTP basic auth password
 */
- (void)setAuthorizationHeaderFieldWithUsername:(NSString *)username
                                       password:(NSString *)password;

/**
 Clears any existing value for the "Authorization" HTTP header.
 */
- (void)clearAuthorizationHeader;

///-------------------------------------------------------
/// @name Configuring Query String Parameter Serialization
///-------------------------------------------------------

/**
 HTTP methods for which serialized requests will encode parameters as a query string. `GET`, `HEAD`, and `DELETE` by default.
 */
@property (nonatomic, strong) NSSet <NSString *> *HTTPMethodsEncodingParametersInURI;


/**
 Set the method of query string serialization according to one of the pre-defined styles.

 @param style The serialization style.

 @see AFHTTPRequestQueryStringSerializationStyle
 */
- (void)setQueryStringSerializationWithStyle:(AFHTTPRequestQueryStringSerializationStyle)style;

/**
 Set the a custom method of query string serialization according to the specified block.

 @param block A block that defines a process of encoding parameters into a query string. This block returns the query string and takes three arguments: the request, the parameters to encode, and the error that occurred when attempting to encode parameters for the given request.
 */
- (void)setQueryStringSerializationWithBlock:(nullable NSString * _Nullable (^)(NSURLRequest *request, id parameters, NSError * __autoreleasing *error))block;

///-------------------------------
/// @name Creating Request Objects
///-------------------------------

/**
 Creates an `NSMutableURLRequest` object with the specified HTTP method and URL string.

 If the HTTP method is `GET`, `HEAD`, or `DELETE`, the parameters will be used to construct a url-encoded query string that is appended to the request's URL. Otherwise, the parameters will be encoded according to the value of the `parameterEncoding` property, and set as the request body.

 @param method The HTTP method for the request, such as `GET`, `POST`, `PUT`, or `DELETE`. This parameter must not be `nil`.
 @param URLString The URL string used to create the request URL.
 @param parameters The parameters to be either set as a query string for `GET` requests, or the request HTTP body.
 @param error The error that occurred while constructing the request.

 @return An `NSMutableURLRequest` object.
 */
- (nullable NSMutableURLRequest *)requestWithMethod:(NSString *)method
                                          URLString:(NSString *)URLString
                                         parameters:(nullable id)parameters
                                              error:(NSError * _Nullable __autoreleasing *)error;

/**
 Creates an `NSMutableURLRequest` object with the specified HTTP method and URLString, and constructs a `multipart/form-data` HTTP body, using the specified parameters and multipart form data block. See http://www.w3.org/TR/html4/interact/forms.html#h-17.13.4.2

 Multipart form requests are automatically streamed, reading files directly from disk along with in-memory data in a single HTTP body. The resulting `NSMutableURLRequest` object has an `HTTPBodyStream` property, so refrain from setting `HTTPBodyStream` or `HTTPBody` on this request object, as it will clear out the multipart form body stream.

 @param method The HTTP method for the request. This parameter must not be `GET` or `HEAD`, or `nil`.
 @param URLString The URL string used to create the request URL.
 @param parameters The parameters to be encoded and set in the request HTTP body.
 @param block A block that takes a single argument and appends data to the HTTP body. The block argument is an object adopting the `AFMultipartFormData` protocol.
 @param error The error that occurred while constructing the request.

 @return An `NSMutableURLRequest` object
 */
- (NSMutableURLRequest *)multipartFormRequestWithMethod:(NSString *)method
                                              URLString:(NSString *)URLString
                                             parameters:(nullable NSDictionary <NSString *, id> *)parameters
                              constructingBodyWithBlock:(nullable void (^)(id <AFMultipartFormData> formData))block
                                                  error:(NSError * _Nullable __autoreleasing *)error;

/**
 Creates an `NSMutableURLRequest` by removing the `HTTPBodyStream` from a request, and asynchronously writing its contents into the specified file, invoking the completion handler when finished.

 @param request The multipart form request. The `HTTPBodyStream` property of `request` must not be `nil`.
 @param fileURL The file URL to write multipart form contents to.
 @param handler A handler block to execute.

 @discussion There is a bug in `NSURLSessionTask` that causes requests to not send a `Content-Length` header when streaming contents from an HTTP body, which is notably problematic when interacting with the Amazon S3 webservice. As a workaround, this method takes a request constructed with `multipartFormRequestWithMethod:URLString:parameters:constructingBodyWithBlock:error:`, or any other request with an `HTTPBodyStream`, writes the contents to the specified file and returns a copy of the original request with the `HTTPBodyStream` property set to `nil`. From here, the file can either be passed to `AFURLSessionManager -uploadTaskWithRequest:fromFile:progress:completionHandler:`, or have its contents read into an `NSData` that's assigned to the `HTTPBody` property of the request.

 @see https://github.com/AFNetworking/AFNetworking/issues/1398
 */
- (NSMutableURLRequest *)requestWithMultipartFormRequest:(NSURLRequest *)request
                             writingStreamContentsToFile:(NSURL *)fileURL
                                       completionHandler:(nullable void (^)(NSError * _Nullable error))handler;

/**
 Returns a percent-escaped string following RFC 3986 for a query string key or value.
 RFC 3986 states that the following characters are "reserved" characters.
    - General Delimiters: ":", "#", "[", "]", "@", "?", "/"
    - Sub-Delimiters: "!", "$", "&", "'", "(", ")", "*", "+", ",", ";", "="

 In RFC 3986 - Section 3.4, it states that the "?" and "/" characters should not be escaped to allow
 query strings to include a URL. Therefore, all "reserved" characters with the exception of "?" and "/"
 should be percent-escaped in the query string.
    - parameter string: The string to be percent-escaped.
    - returns: The percent-escaped string.
 */
NSString * AFPercentEscapedStringFromString(NSString *string) {
    static NSString * const kAFCharactersGeneralDelimitersToEncode = @":#[]@"; // does not include "?" or "/" due to RFC 3986 - Section 3.4
    static NSString * const kAFCharactersSubDelimitersToEncode = @"!$&'()*+,;=";

    NSMutableCharacterSet * allowedCharacterSet = [[NSCharacterSet URLQueryAllowedCharacterSet] mutableCopy];
    [allowedCharacterSet removeCharactersInString:[kAFCharactersGeneralDelimitersToEncode stringByAppendingString:kAFCharactersSubDelimitersToEncode]];

	// FIXME: https://github.com/AFNetworking/AFNetworking/pull/3028
    // return [string stringByAddingPercentEncodingWithAllowedCharacters:allowedCharacterSet];

    static NSUInteger const batchSize = 50;

    NSUInteger index = 0;
    NSMutableString *escaped = @"".mutableCopy;

    while (index < string.length) {
        NSUInteger length = MIN(string.length - index, batchSize);
        NSRange range = NSMakeRange(index, length);

        // To avoid breaking up character sequences such as 👴🏻👮🏽
        range = [string rangeOfComposedCharacterSequencesForRange:range];

        NSString *substring = [string substringWithRange:range];
        NSString *encoded = [substring stringByAddingPercentEncodingWithAllowedCharacters:allowedCharacterSet];
        [escaped appendString:encoded];

        index += range.length;
    }

	return escaped;
}

@implementation AFHTTPRequestSerializer

+ (instancetype)serializer {
    return [[self alloc] init];
}

- (instancetype)init {
    self = [super init];
    if (!self) {
        return nil;
    }

    self.stringEncoding = NSUTF8StringEncoding;

    self.mutableHTTPRequestHeaders = [NSMutableDictionary dictionary];
    self.requestHeaderModificationQueue = dispatch_queue_create("requestHeaderModificationQueue", DISPATCH_QUEUE_CONCURRENT);

    // Accept-Language HTTP Header; see http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.4
    NSMutableArray *acceptLanguagesComponents = [NSMutableArray array];
    [[NSLocale preferredLanguages] enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        float q = 1.0f - (idx * 0.1f);
        [acceptLanguagesComponents addObject:[NSString stringWithFormat:@"%@;q=%0.1g", obj, q]];
        *stop = q <= 0.5f;
    }];
    [self setValue:[acceptLanguagesComponents componentsJoinedByString:@", "] forHTTPHeaderField:@"Accept-Language"];

    // User-Agent Header; see http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.43
    NSString *userAgent = nil;
#if TARGET_OS_IOS
    userAgent = [NSString stringWithFormat:@"%@/%@ (%@; iOS %@; Scale/%0.2f)", [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleExecutableKey] ?: [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleIdentifierKey], [[NSBundle mainBundle] infoDictionary][@"CFBundleShortVersionString"] ?: [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleVersionKey], [[UIDevice currentDevice] model], [[UIDevice currentDevice] systemVersion], [[UIScreen mainScreen] scale]];
#elif TARGET_OS_TV
    userAgent = [NSString stringWithFormat:@"%@/%@ (%@; tvOS %@; Scale/%0.2f)", [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleExecutableKey] ?: [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleIdentifierKey], [[NSBundle mainBundle] infoDictionary][@"CFBundleShortVersionString"] ?: [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleVersionKey], [[UIDevice currentDevice] model], [[UIDevice currentDevice] systemVersion], [[UIScreen mainScreen] scale]];
#elif TARGET_OS_WATCH
    userAgent = [NSString stringWithFormat:@"%@/%@ (%@; watchOS %@; Scale/%0.2f)", [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleExecutableKey] ?: [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleIdentifierKey], [[NSBundle mainBundle] infoDictionary][@"CFBundleShortVersionString"] ?: [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleVersionKey], [[WKInterfaceDevice currentDevice] model], [[WKInterfaceDevice currentDevice] systemVersion], [[WKInterfaceDevice currentDevice] screenScale]];
#elif defined(__MAC_OS_X_VERSION_MIN_REQUIRED)
    userAgent = [NSString stringWithFormat:@"%@/%@ (Mac OS X %@)", [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleExecutableKey] ?: [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleIdentifierKey], [[NSBundle mainBundle] infoDictionary][@"CFBundleShortVersionString"] ?: [[NSBundle mainBundle] infoDictionary][(__bridge NSString *)kCFBundleVersionKey], [[NSProcessInfo processInfo] operatingSystemVersionString]];
#endif
    if (userAgent) {
        if (![userAgent canBeConvertedToEncoding:NSASCIIStringEncoding]) {
            NSMutableString *mutableUserAgent = [userAgent mutableCopy];
            if (CFStringTransform((__bridge CFMutableStringRef)(mutableUserAgent), NULL, (__bridge CFStringRef)@"Any-Latin; Latin-ASCII; [:^ASCII:] Remove", false)) {
                userAgent = mutableUserAgent;
            }
        }
        [self setValue:userAgent forHTTPHeaderField:@"User-Agent"];
    }

    // HTTP Method Definitions; see http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html
    self.HTTPMethodsEncodingParametersInURI = [NSSet setWithObjects:@"GET", @"HEAD", @"DELETE", nil];

    self.mutableObservedChangedKeyPaths = [NSMutableSet set];
    for (NSString *keyPath in AFHTTPRequestSerializerObservedKeyPaths()) {
        if ([self respondsToSelector:NSSelectorFromString(keyPath)]) {
            [self addObserver:self forKeyPath:keyPath options:NSKeyValueObservingOptionNew context:AFHTTPRequestSerializerObserverContext];
        }
    }

    return self;
}

- (void)dealloc {
    for (NSString *keyPath in AFHTTPRequestSerializerObservedKeyPaths()) {
        if ([self respondsToSelector:NSSelectorFromString(keyPath)]) {
            [self removeObserver:self forKeyPath:keyPath context:AFHTTPRequestSerializerObserverContext];
        }
    }
}

#pragma mark -

// Workarounds for crashing behavior using Key-Value Observing with XCTest
// See https://github.com/AFNetworking/AFNetworking/issues/2523

- (void)setAllowsCellularAccess:(BOOL)allowsCellularAccess {
    [self willChangeValueForKey:NSStringFromSelector(@selector(allowsCellularAccess))];
    _allowsCellularAccess = allowsCellularAccess;
    [self didChangeValueForKey:NSStringFromSelector(@selector(allowsCellularAccess))];
}

- (void)setCachePolicy:(NSURLRequestCachePolicy)cachePolicy {
    [self willChangeValueForKey:NSStringFromSelector(@selector(cachePolicy))];
    _cachePolicy = cachePolicy;
    [self didChangeValueForKey:NSStringFromSelector(@selector(cachePolicy))];
}

- (void)setHTTPShouldHandleCookies:(BOOL)HTTPShouldHandleCookies {
    [self willChangeValueForKey:NSStringFromSelector(@selector(HTTPShouldHandleCookies))];
    _HTTPShouldHandleCookies = HTTPShouldHandleCookies;
    [self didChangeValueForKey:NSStringFromSelector(@selector(HTTPShouldHandleCookies))];
}

- (void)setHTTPShouldUsePipelining:(BOOL)HTTPShouldUsePipelining {
    [self willChangeValueForKey:NSStringFromSelector(@selector(HTTPShouldUsePipelining))];
    _HTTPShouldUsePipelining = HTTPShouldUsePipelining;
    [self didChangeValueForKey:NSStringFromSelector(@selector(HTTPShouldUsePipelining))];
}

- (void)setNetworkServiceType:(NSURLRequestNetworkServiceType)networkServiceType {
    [self willChangeValueForKey:NSStringFromSelector(@selector(networkServiceType))];
    _networkServiceType = networkServiceType;
    [self didChangeValueForKey:NSStringFromSelector(@selector(networkServiceType))];
}

- (void)setTimeoutInterval:(NSTimeInterval)timeoutInterval {
    [self willChangeValueForKey:NSStringFromSelector(@selector(timeoutInterval))];
    _timeoutInterval = timeoutInterval;
    [self didChangeValueForKey:NSStringFromSelector(@selector(timeoutInterval))];
}

#pragma mark -

- (NSDictionary *)HTTPRequestHeaders {
    NSDictionary __block *value;
    dispatch_sync(self.requestHeaderModificationQueue, ^{
        value = [NSDictionary dictionaryWithDictionary:self.mutableHTTPRequestHeaders];
    });
    return value;
}

- (void)setValue:(NSString *)value
forHTTPHeaderField:(NSString *)field
{
    dispatch_barrier_sync(self.requestHeaderModificationQueue, ^{
        [self.mutableHTTPRequestHeaders setValue:value forKey:field];
    });
}

- (NSString *)valueForHTTPHeaderField:(NSString *)field {
    NSString __block *value;
    dispatch_sync(self.requestHeaderModificationQueue, ^{
        value = [self.mutableHTTPRequestHeaders valueForKey:field];
    });
    return value;
}

- (void)setAuthorizationHeaderFieldWithUsername:(NSString *)username
                                       password:(NSString *)password
{
    NSData *basicAuthCredentials = [[NSString stringWithFormat:@"%@:%@", username, password] dataUsingEncoding:NSUTF8StringEncoding];
    NSString *base64AuthCredentials = [basicAuthCredentials base64EncodedStringWithOptions:(NSDataBase64EncodingOptions)0];
    [self setValue:[NSString stringWithFormat:@"Basic %@", base64AuthCredentials] forHTTPHeaderField:@"Authorization"];
}

- (void)clearAuthorizationHeader {
    dispatch_barrier_sync(self.requestHeaderModificationQueue, ^{
        [self.mutableHTTPRequestHeaders removeObjectForKey:@"Authorization"];
    });
}

#pragma mark -

- (void)setQueryStringSerializationWithStyle:(AFHTTPRequestQueryStringSerializationStyle)style {
    self.queryStringSerializationStyle = style;
    self.queryStringSerialization = nil;
}

- (void)setQueryStringSerializationWithBlock:(NSString *(^)(NSURLRequest *, id, NSError *__autoreleasing *))block {
    self.queryStringSerialization = block;
}

#pragma mark -

- (NSMutableURLRequest *)requestWithMethod:(NSString *)method
                                 URLString:(NSString *)URLString
                                parameters:(id)parameters
                                     error:(NSError *__autoreleasing *)error
{
    NSParameterAssert(method);
    NSParameterAssert(URLString);

    NSURL *url = [NSURL URLWithString:URLString];

    NSParameterAssert(url);

    NSMutableURLRequest *mutableRequest = [[NSMutableURLRequest alloc] initWithURL:url];
    mutableRequest.HTTPMethod = method;

    for (NSString *keyPath in self.mutableObservedChangedKeyPaths) {
        [mutableRequest setValue:[self valueForKeyPath:keyPath] forKey:keyPath];
    }

    mutableRequest = [[self requestBySerializingRequest:mutableRequest withParameters:parameters error:error] mutableCopy];

	return mutableRequest;
}

- (NSMutableURLRequest *)multipartFormRequestWithMethod:(NSString *)method
                                              URLString:(NSString *)URLString
                                             parameters:(NSDictionary *)parameters
                              constructingBodyWithBlock:(void (^)(id <AFMultipartFormData> formData))block
                                                  error:(NSError *__autoreleasing *)error
{
    NSParameterAssert(method);
    NSParameterAssert(![method isEqualToString:@"GET"] && ![method isEqualToString:@"HEAD"]);

    NSMutableURLRequest *mutableRequest = [self requestWithMethod:method URLString:URLString parameters:nil error:error];

    __block AFStreamingMultipartFormData *formData = [[AFStreamingMultipartFormData alloc] initWithURLRequest:mutableRequest stringEncoding:NSUTF8StringEncoding];
// 处理常规formData
    if (parameters) {
        for (AFQueryStringPair *pair in AFQueryStringPairsFromDictionary(parameters)) {
            NSData *data = nil;
            if ([pair.value isKindOfClass:[NSData class]]) {
                data = pair.value;
            } else if ([pair.value isEqual:[NSNull null]]) {
                data = [NSData data];
            } else {
                data = [[pair.value description] dataUsingEncoding:self.stringEncoding];
            }

            if (data) {
                [formData appendPartWithFormData:data name:[pair.field description]];
            }
        }
    }
// 通过block可进一步添加其他如文件的formData
    if (block) {
        block(formData);
    }

    return [formData requestByFinalizingMultipartFormData];
}

// 读取multipartFormRequst的数据到fileURL
- (NSMutableURLRequest *)requestWithMultipartFormRequest:(NSURLRequest *)request
                             writingStreamContentsToFile:(NSURL *)fileURL
                                       completionHandler:(void (^)(NSError *error))handler
{
    NSParameterAssert(request.HTTPBodyStream);
    NSParameterAssert([fileURL isFileURL]);

    NSInputStream *inputStream = request.HTTPBodyStream;
    NSOutputStream *outputStream = [[NSOutputStream alloc] initWithURL:fileURL append:NO];
    __block NSError *error = nil;

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        [inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
        [outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

        [inputStream open];
        [outputStream open];

      // 读取操作
        while ([inputStream hasBytesAvailable] && [outputStream hasSpaceAvailable]) {
            uint8_t buffer[1024];

            NSInteger bytesRead = [inputStream read:buffer maxLength:1024];
            if (inputStream.streamError || bytesRead < 0) {
                error = inputStream.streamError;
                break;
            }

            NSInteger bytesWritten = [outputStream write:buffer maxLength:(NSUInteger)bytesRead];
            if (outputStream.streamError || bytesWritten < 0) {
                error = outputStream.streamError;
                break;
            }

            if (bytesRead == 0 && bytesWritten == 0) {
                break;
            }
        }

        [outputStream close];
        [inputStream close];

        if (handler) {
            dispatch_async(dispatch_get_main_queue(), ^{
                handler(error);
            });
        }
    });

    NSMutableURLRequest *mutableRequest = [request mutableCopy];
    mutableRequest.HTTPBodyStream = nil;

    return mutableRequest;
}

#pragma mark - AFURLRequestSerialization

- (NSURLRequest *)requestBySerializingRequest:(NSURLRequest *)request
                               withParameters:(id)parameters
                                        error:(NSError *__autoreleasing *)error
{
    NSParameterAssert(request);

    NSMutableURLRequest *mutableRequest = [request mutableCopy];

    [self.HTTPRequestHeaders enumerateKeysAndObjectsUsingBlock:^(id field, id value, BOOL * __unused stop) {
        if (![request valueForHTTPHeaderField:field]) {
            [mutableRequest setValue:value forHTTPHeaderField:field];
        }
    }];

    NSString *query = nil;
    if (parameters) {
        if (self.queryStringSerialization) {
            NSError *serializationError;
            query = self.queryStringSerialization(request, parameters, &serializationError);

            if (serializationError) {
                if (error) {
                    *error = serializationError;
                }

                return nil;
            }
        } else {
            switch (self.queryStringSerializationStyle) {
                case AFHTTPRequestQueryStringDefaultStyle:
                    query = AFQueryStringFromParameters(parameters);
                    break;
            }
        }
    }

    if ([self.HTTPMethodsEncodingParametersInURI containsObject:[[request HTTPMethod] uppercaseString]]) {
        if (query && query.length > 0) {
            mutableRequest.URL = [NSURL URLWithString:[[mutableRequest.URL absoluteString] stringByAppendingFormat:mutableRequest.URL.query ? @"&%@" : @"?%@", query]];
        }
    } else {
        // #2864: an empty string is a valid x-www-form-urlencoded payload
        if (!query) {
            query = @"";
        }
        if (![mutableRequest valueForHTTPHeaderField:@"Content-Type"]) {
            [mutableRequest setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
        }
        [mutableRequest setHTTPBody:[query dataUsingEncoding:self.stringEncoding]];
    }

    return mutableRequest;
}

#pragma mark - NSKeyValueObserving

+ (BOOL)automaticallyNotifiesObserversForKey:(NSString *)key {
    if ([AFHTTPRequestSerializerObservedKeyPaths() containsObject:key]) {
        return NO;
    }

    return [super automaticallyNotifiesObserversForKey:key];
}

- (void)observeValueForKeyPath:(NSString *)keyPath
                      ofObject:(__unused id)object
                        change:(NSDictionary *)change
                       context:(void *)context
{
    if (context == AFHTTPRequestSerializerObserverContext) {
        if ([change[NSKeyValueChangeNewKey] isEqual:[NSNull null]]) {
            [self.mutableObservedChangedKeyPaths removeObject:keyPath];
        } else {
            [self.mutableObservedChangedKeyPaths addObject:keyPath];
        }
    }
}

#pragma mark - NSSecureCoding

+ (BOOL)supportsSecureCoding {
    return YES;
}

- (instancetype)initWithCoder:(NSCoder *)decoder {
    self = [self init];
    if (!self) {
        return nil;
    }
// secure decoding
    self.mutableHTTPRequestHeaders = [[decoder decodeObjectOfClass:[NSDictionary class] forKey:NSStringFromSelector(@selector(mutableHTTPRequestHeaders))] mutableCopy];
    self.queryStringSerializationStyle = (AFHTTPRequestQueryStringSerializationStyle)[[decoder decodeObjectOfClass:[NSNumber class] forKey:NSStringFromSelector(@selector(queryStringSerializationStyle))] unsignedIntegerValue];

    return self;
}

- (void)encodeWithCoder:(NSCoder *)coder {
    dispatch_sync(self.requestHeaderModificationQueue, ^{
        [coder encodeObject:self.mutableHTTPRequestHeaders forKey:NSStringFromSelector(@selector(mutableHTTPRequestHeaders))];
    });
    [coder encodeObject:@(self.queryStringSerializationStyle) forKey:NSStringFromSelector(@selector(queryStringSerializationStyle))];
}

#pragma mark - NSCopying

- (instancetype)copyWithZone:(NSZone *)zone {
    AFHTTPRequestSerializer *serializer = [[[self class] allocWithZone:zone] init];
    dispatch_sync(self.requestHeaderModificationQueue, ^{
        serializer.mutableHTTPRequestHeaders = [self.mutableHTTPRequestHeaders mutableCopyWithZone:zone];
    });
    serializer.queryStringSerializationStyle = self.queryStringSerializationStyle;
    serializer.queryStringSerialization = self.queryStringSerialization;

    return serializer;
}

@end

/**
 `AFJSONRequestSerializer` is a subclass of `AFHTTPRequestSerializer` that encodes parameters as JSON using `NSJSONSerialization`, setting the `Content-Type` of the encoded request to `application/json`.
 */
@interface AFJSONRequestSerializer : AFHTTPRequestSerializer

/**
 Options for writing the request JSON data from Foundation objects. For possible values, see the `NSJSONSerialization` documentation section "NSJSONWritingOptions". `0` by default.
 */
@property (nonatomic, assign) NSJSONWritingOptions writingOptions;

/**
 Creates and returns a JSON serializer with specified reading and writing options.

 @param writingOptions The specified JSON writing options.
 */
+ (instancetype)serializerWithWritingOptions:(NSJSONWritingOptions)writingOptions;

@end

- (NSURLRequest *)requestBySerializingRequest:(NSURLRequest *)request
                               withParameters:(id)parameters
                                        error:(NSError *__autoreleasing *)error
{
    NSParameterAssert(request);

    if ([self.HTTPMethodsEncodingParametersInURI containsObject:[[request HTTPMethod] uppercaseString]]) {
        return [super requestBySerializingRequest:request withParameters:parameters error:error];
    }

    NSMutableURLRequest *mutableRequest = [request mutableCopy];

    [self.HTTPRequestHeaders enumerateKeysAndObjectsUsingBlock:^(id field, id value, BOOL * __unused stop) {
        if (![request valueForHTTPHeaderField:field]) {
            [mutableRequest setValue:value forHTTPHeaderField:field];
        }
    }];

    if (parameters) {
        if (![mutableRequest valueForHTTPHeaderField:@"Content-Type"]) {
            [mutableRequest setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
        }

        if (![NSJSONSerialization isValidJSONObject:parameters]) {
            if (error) {
                NSDictionary *userInfo = @{NSLocalizedFailureReasonErrorKey: NSLocalizedStringFromTable(@"The `parameters` argument is not valid JSON.", @"AFNetworking", nil)};
                *error = [[NSError alloc] initWithDomain:AFURLRequestSerializationErrorDomain code:NSURLErrorCannotDecodeContentData userInfo:userInfo];
            }
            return nil;
        }

        NSData *jsonData = [NSJSONSerialization dataWithJSONObject:parameters options:self.writingOptions error:error];
        
        if (!jsonData) {
            return nil;
        }
        
        [mutableRequest setHTTPBody:jsonData];
    }

    return mutableRequest;
}

/**
 `AFPropertyListRequestSerializer` is a subclass of `AFHTTPRequestSerializer` that encodes parameters as JSON using `NSPropertyListSerializer`, setting the `Content-Type` of the encoded request to `application/x-plist`.
 */
@interface AFPropertyListRequestSerializer : AFHTTPRequestSerializer

/**
 The property list format. Possible values are described in "NSPropertyListFormat".
 */
@property (nonatomic, assign) NSPropertyListFormat format;

/**
 @warning The `writeOptions` property is currently unused.
 */
@property (nonatomic, assign) NSPropertyListWriteOptions writeOptions;

/**
 Creates and returns a property list serializer with a specified format, read options, and write options.

 @param format The property list format.
 @param writeOptions The property list write options.

 @warning The `writeOptions` property is currently unused.
 */
+ (instancetype)serializerWithFormat:(NSPropertyListFormat)format
                        writeOptions:(NSPropertyListWriteOptions)writeOptions;

@end

- (NSURLRequest *)requestBySerializingRequest:(NSURLRequest *)request
                               withParameters:(id)parameters
                                        error:(NSError *__autoreleasing *)error
{
    NSParameterAssert(request);

    if ([self.HTTPMethodsEncodingParametersInURI containsObject:[[request HTTPMethod] uppercaseString]]) {
        return [super requestBySerializingRequest:request withParameters:parameters error:error];
    }

    NSMutableURLRequest *mutableRequest = [request mutableCopy];

    [self.HTTPRequestHeaders enumerateKeysAndObjectsUsingBlock:^(id field, id value, BOOL * __unused stop) {
        if (![request valueForHTTPHeaderField:field]) {
            [mutableRequest setValue:value forHTTPHeaderField:field];
        }
    }];

    if (parameters) {
        if (![mutableRequest valueForHTTPHeaderField:@"Content-Type"]) {
            [mutableRequest setValue:@"application/x-plist" forHTTPHeaderField:@"Content-Type"];
        }

        NSData *plistData = [NSPropertyListSerialization dataWithPropertyList:parameters format:self.format options:self.writeOptions error:error];
        
        if (!plistData) {
            return nil;
        }
        
        [mutableRequest setHTTPBody:plistData];
    }

    return mutableRequest;
}