title: UIImage Scale Aspect Fill and Clip Subviews not working in UICollectionView
body: <p>I have a UICollectionView with a cell containing a single UIImageView. I'm setting the UIImageView frame.size to match the cell's frame.size and also explicitly asking the UIImageView to Scale with Aspect Fill &amp; Clip Subview the following way in <strong><em>cellForItemAtIndexPath</em></strong> method:</p>
  
  <pre><code>let cell:UICollectionViewCell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath) as! UICollectionViewCell
  
  ... 
  
  var imageView = UIImageView(image: self.eventImages[indexPath.row])
  imageView.frame.size = cell.frame.size
  cell.contentMode = UIViewContentMode.ScaleAspectFill
  cell.clipsToBounds = true
  imageView.contentMode = UIViewContentMode.ScaleAspectFill
  imageView.clipsToBounds = true
  cell.addSubview(imageView)
  </code></pre>
  
  <p>The result is a stretched out image <strong>(IMAGE A)</strong>, but when I click (tap) the image it "magically" resolves the Aspect Fill &amp; Clip Subviews <strong>(IMAGE B)</strong> . I can't seem to understand why this is happening only after a tap and not when loading the images for the first time. They are fetched asynchronously to a server, but the scaling only occurs after a tap of the image (there is also no tap functionality implemented).</p>
  
  <p>NOTE: The UICollectionView is set up in a storyboard View Controller, both the Collection View and the Reusable Cell have Aspect Fill and Clip Subviews enabled.</p>
  
  <h2><strong>IMAGE A (wrong scaling - stretched out and no cropping):</strong></h2>
  
  <p><img src="https://i.stack.imgur.com/JkoaU.png" alt="IMG A"></p>
  
  <h2><strong>IMAGE B (correct scaling after tap):</strong></h2>
  
  <p><img src="https://i.stack.imgur.com/bxwzB.png" alt="IMG B"></p>