title: Weird animation behaviour with UICollectionView (insert & delete item)
body: <p>When inserting or deleting an item from a UICollectionView, it seems like an extra cell appears during the animation, and this extra cell moves in the wrong direction. I've tried exactly the same with a UITableView, and there is no problem.</p>
  
  <p>A <strong>video of the problem is here</strong>: <a href="https://dl.dropbox.com/u/11523469/CollectionViewBug.mov" rel="noreferrer">https://dl.dropbox.com/u/11523469/CollectionViewBug.mov</a>, with the collection view on the left and the table view on the right. The number in each cell is the indexPath.item value of the cell when the cell is created.</p>
  
  <p>The problem is first noticeable in the video between 0:08 and 0:12 (insert) and then again at 0:16 to 0:20 (delete).</p>
  
  <p>The <strong>project is available here</strong>: <a href="https://dl.dropbox.com/u/11523469/CollectionViewBug.zip" rel="noreferrer">https://dl.dropbox.com/u/11523469/CollectionViewBug.zip</a></p>
  
  <p>i.e. when inserting a cell, all cells below where the cell is being inserted move down to make room for the new cell. But this extra cell appears and overlaps the others and moves up.</p>
  
  <p>Likewise, when deleting a cell, all cells below the cell being deleted move up to fill the gap where the cell used to be. But this extra cell appears and overlaps the others and moves down.</p>
  
  <p>The first action to be performed on the collection view, either insert or delete, does not cause this problem. But on all subsequent actions the problem is there.</p>
  
  <p>Has anyone else experienced the same problem with UICollectionView? Does anyone have a solution or workaround?</p>
  
  <p>Thanks!</p>