Core Animation is a graphics rendering and animation infrastructure available on both iOS and OS X that you use to animate the views and other visual elements of your app.
With Core Animation, most of the work required to draw each frame of an animation is done for you.
All you have to do is configure a few animation parameters (such as the start and end points) and tell Core Animation to start. Core Animation does the rest, handing most of the actual drawing work off to the onboard graphics hardware to accelerate the rendering.
This automatic graphics acceleration results in high frame rates and smooth animations without burdening the CPU and slowing down your app.
Core Animation Manages Your App’s Content
Core Animation is not a drawing system itself. It is an infrastructure for compositing and manipulating your app’s content in hardware. At the heart of this infrastructure are layer objects, which you use to manage and manipulate your content. A layer captures your content into a bitmap that can be manipulated easily by the graphics hardware. In most apps, layers are used as a way to manage the content of views but you can also create standalone layers depending on your needs.