title: UIScrollView bounce end event
body: <p>Maybe I made a wrong description for what I want and hence haven't hit any answer, if that's the case please kindly provide a link with solution.</p>
  
  <p>what I want is:
  I have scrollview, alwaysBounceVertical is set to true. So when the user drags down after the scrollview has already reached top, the scrollview should bounce. More specific: the view moves down as the user drags, and the moment the user releases his finger the scrollview bounces back. </p>
  
  <p>The event I want to catch is the one that the scrollview finishes bouncing back. I want to apply an animation after this point. So could anyone tell me how should I modify which method in UIScrollViewDelegate to catch that event?</p>