title: Independent scrolling for each section of a UICollectionView?
body: <p>Is it possible to use <code>UICollectionView</code> to build a layout where each <strong>section</strong> can be independently scrolled?  For example, imagine 20 rows of images, where each row could be scrolled independently horizontally to reveal more images offscreen (without scrolling other rows in the process); and the entire view could be scrolled vertically to reveal more rows.  </p>
  
  <p>I believe something like this could be implemented with several instances of UICollectionView inside a UIScrollView; however, it'd be great to leverage UICollectionView for inserting/moving sections.</p>
  
  <p>I suspect this isn't practical since UICollectionView is a subclass of UIScrollView; but perhaps this can be done with a custom UICollectionViewLayout?</p>