Collapse or expand UIView using UIPanGestureRecognizer in iOS

I want to expand and collapse multiple UIView using UIPanGestureRecognizer.

For reference you can see this link: https://itunes.apple.com/us/app/fleck-the-bigger-picture/id619977675?mt=8

I have used facebook pop library on github : https://github.com/facebook/pop. Uding this I am able to expand and collapse using POPSpringAnimation. But the problem is that I want to expand or collapse UIView as user pan i.e one view will collapse and other will expand.

Is there any library using which I can do this stuff?