title: Make UICollectionView zoomable?
body: <p>Is there any method make the <code>UICollectionView</code> <code>zoomable</code>, i.e. when you pinch, all the cells can be zoomed in and out.<br>
  I can implement this in <code>UIScrollView</code> by returning the only <code>subview</code> of the <code>UIScrollView</code> from <code>delegate</code> method  </p>
  
  <pre><code>- (UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView
  </code></pre>
  
  <p>Since <code>UICollectionView</code> is kind of <code>UIScrollView</code>, is there a way or work around to implement this? Does the <code>UICollectionView</code> has one direct subview that contains all cells?<br>
  Thanks</p>