How to rotate a square UIImage relative to it's one corner?

I want rotate a square UIImage relative to one of开发者_StackOverflow中文版 it's corner, for example, it's top left corner, how can I do it in a simple way?

Check out this open source project: KitchenSink, you will want to take a look at the Anchor Point Animation example. It will show you how to animate a box at each corner.