UIFXKit is a layer of OpenGL that sits on top of UIKit and allows OpenGL powered effects and transitions between views.
Simply use UIFXWindow as your application window, pass in the UIBaseEffect subclass of your choosing or write your own. When an effect is triggered, the library takes a snap shot image of the current UIKit view heirarchy and uses that as a texture for the transition by wrapping it around a 3D model defined in the effect. From there it is up to the effect to determine what happens. You could make it appear that the UIKit UI folds up into a paper airplane, and flies away, you could write a shader to make it appear that the interface is on fire, you could make it melt off the screen. Using OpenGL and shader technology anything is possible.