CALayer rotation in iOS
This is just a work I did to implement the rotation of a CALayer in iOS, it was pretty much inspired by Roambi's excellent pie chart. I decided to share it after a lot of polish and IMHO the algorithm was simple enough to share it.
If you did not reach this page via my personal blog then here it is http://devlogx.blogspot.mx/2012/03/calayer-rotation-in-ios.html, there you can find a detail explanation of the code.