title: zoom entire UICollectionView
body: <p>I have an iPad App where I'm using a UICollectionView and each UICollectionViewCell contains just a single UIImage.
  Currently I'm displaying per 9 UIImages (3 rows * 3 columns) per page, I have several pages.</p>
  
  <p>I would like to use Pinch Gesture to zoom on the entire UICollectionView to increase/decrease the number of row/columns displayed per page and the best would be to have beautiful zoom animation during the Pinch gesture! </p>
  
  <p>Currently, I have added a Pinch Gesture on my UICollectionView. I catch the Pinch Gesture event to compute the number of rows/columns using the scale factor, if it has changed then I update the full UICollectionView using: </p>
  
  <pre><code>[_theCollectionView performBatchUpdates:^{
       [_theCollectionView deleteSections:[NSIndexSet indexSetWithIndex:0]];
       [_theCollectionView insertSections:[NSIndexSet indexSetWithIndex:0]];
   } completion:nil];
  </code></pre>
  
  <p>It works but I don't have smooth animation during the transition.</p>
  
  <p>Any idea? UICollectionView inherits from UIScrollView, is there a possibility to re-use the UIScrollView Pinch gesture feature to reach my goal?</p>