title: UICollectionView reloadData not functioning properly in iOS 7
body: <p>I've been updating my apps to run on iOS 7 which is going smoothly for the most part. I have noticed in more than one app that the <code>reloadData</code> method of a <code>UICollectionViewController</code> isn't acting quite how it used to. </p>
  
  <p>I'll load the <code>UICollectionViewController</code>, populate the <code>UICollectionView</code> with some data as normal. This works great on the first time. However if I request new data (populate the <code>UICollectionViewDataSource</code>), and then call <code>reloadData</code>, it will query the data source for <code>numberOfItemsInSection</code> and <code>numberOfSectionsInCollectionView</code>, but it doesn't seem to call <code>cellForItemAtIndexPath</code> the proper number of times. </p>
  
  <p>If I change the code to only reload one section, then it will function properly. This is no problem for me to change these, but I don't think I should have to. <code>reloadData</code> should reload all visible cells according to the documentation. </p>
  
  <p>Has anyone else seen this?</p>