UIView rounded rect mask (only some corners)
UIView shaped like a bezier path http://stackoverflow.com/questions/11666567/uiview-that-is-shaped-like-a-uibezierpath http://floriankugler.com/blog/2013/5/24/layer-trees-vs-flat-drawing-graphics-performance-across-ios-device-generations taming uibutton http://robots.thoughtbot.com/post/33427366406/designing-for-ios-taming-uibutton