Create Advanced Custom Animations on iOS

Custom animations on iOS:

“INTUAnimationEngine makes it easy to build advanced custom animations on iOS…It enables interactive animations (normally driven by user input, such as a pan or pinch gesture) to run automatically over a given duration. It can also be used to get a callback every frame of an animation.”

And as a bonus:

“…A complete library of interpolation functions is also included to animate any type of value or property, including those that are not animatable by Core Animation.”