title: Detected a case where constraints ambiguously suggest a size of zero for a collection view cell's content view
body: <p>Has anyone got this problem with CollectionView?</p>
  
  <pre><code>Warning once only: Detected a case where constraints ambiguously suggest a size of zero for a
  collection view cell's content view. We're considering the collapse unintentional and using 
  standard size instead.
  </code></pre>
  
  <p>I have added custom CollectionViewCell with xib in CollectionView.  </p>