ScrollView의 스크롤이 끝났을 때의 이벤트

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
  if (!decelerate)
    [self postScrollExplosion:scrollView];
}

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
  [self postScrollExplosion:scrollView];
}

[출처] http://keighl.com/post/did-uiscrollview-end-scrolling/