SONFrameAnimation is an iOS class that supports to display still frames of desired position in your custom animation.
It allows you to perform ‘animate as you pinch (or pan, scroll) effect’, and also can animate forward or backward from the specific position.
SONFrameAnimationGroup is a group of animations. By using this class, you can create more complex custom animations by grouping severalSONFrameAnimation objects. Features in SONFrameAnimation such as still frame, resume, and rewind animation can also be used with the group.
Find the source code in my github page.