Core Animation is the built in animation facility of OS X that is built on top of OpenGL. It’s available on the iPhone. This article is interesting for anyone looking into designing games for the iPhone.
http://cocoawithlove.com/2009/02/asteroids-style-game-in-coreanimation.html
http://cocoawithlove.com/2009/02/asteroids-style-game-in-coreanimation_22.html