title: UICollectionView not able to scroll to see the entire last row
body: <p>I have a UICollectionView with size: <code>768x1024</code> with a navbar on top. My custom <code>UICollectionViewCells</code> are of size <code>200x200</code>. The problem is that when I keep adding cells and I reach the bottom row, I can only see part of the <code>200x200</code> cell. It won't let me scroll further before it bounces back up. Any ideas on what the problem could be?</p>
  
  <p>EDIT:</p>
  
  <p>I add cells via:</p>
  
  <p><code>insertItemsAtIndexPaths:</code></p>