title: Setting UICollectionViewCell size when cell is using AutoLayout
body: <p>I have a <code>UICollectionViewCell</code> that has a dynamic height. It contains a <code>UIWebView</code> that loads some content asynchronously. After load, it needs to resize itself to accommodate its contents.</p>
  
  <p>I do the cell resizing by changing the height constraint of the <code>web view</code>.</p>
  
  <p>I also send a delegate method to the collection <code>view controller</code> that the cell has resized and I need to invalidate layout.</p>
  
  <p>However, I am getting auto layout errors about conflicting constraints. It seems the collection view is trying to resize the cell.</p>
  
  <p>Does anyone know how to make this design work?</p>