How to animate wedge angle changes in iOS

I have a cricle of constant size and a wedge inside of the circle that rotates around the center (like a radar). Radius of that wedge is also constant, but angle of the wedge changes. It can be several degrees and it can be 360.

The wedg开发者_高级运维e is implemented using UIView derived class and Quartz 2D and I can easily animate the rotation using UIView animateWithDuration and CGAffineTransformMakeRotation. Now I am looking for a way to animate the wedge angle changes, with expanding/collapsing showing symmetrically on both sides from axis of the wedge (like if you are opening a fan). I would like to have easing, too.

Can anybody provide any pointers or examples?

Thanks!