title: UICollection View causes "UICollectionViewFlowLayoutBreakForInvalidSizes" on smaller devices
body: <p>On an iPhone 6 Plus, the collection view cells are fine, but when testing on another device size like the iPhone 5, i'm bombarded with "</p>
  
  <blockquote>
    <p>017-06-15 01:59:25.744 HyperTest[3865:8825385] The behavior of the UICollectionViewFlowLayout is not defined because:
    2017-06-15 01:59:25.744 HyperTest[3865:8825385] the item width must be less than the width of the UICollectionView minus the section insets left and right values, minus the content insets left and right values.
    2017-06-15 01:59:25.745 HyperTest[3865:8825385] The relevant UICollectionViewFlowLayout instance is , and it is attached to ; layer = ; contentOffset: {0, 0}; contentSize: {414, 219}> collection view layout: .
    2017-06-15 01:59:25.745 HyperTest[3865:8825385] Make a symbolic breakpoint at UICollectionViewFlowLayoutBreakForInvalidSizes to catch this in the debugger.</p>
  </blockquote>
  
  <p>especially when I do this:</p>
  
  <pre><code>let layout = billFeedCollectionView.collectionViewLayout as? UICollectionViewFlowLayout // casting is required because UICollectionViewLayout doesn't offer header pin. It's feature of UICollectionViewFlowLayout
      layout?.sectionHeadersPinToVisibleBounds = true
      layout?.estimatedItemSize = UICollectionViewFlowLayoutAutomaticSize
  </code></pre>
  
  <p>anyway, I can resolve this problem? I need to ensure that the cell scales and fits all devices.</p>