title: How can I center rows in UICollectionView?
body: <p>I have a <code>UICollectionView</code> with random cells. Is there any method that allows me to center rows?</p>
  
  <p>This is how it looks by default:  </p>
  
  <pre><code>[ x x x x x x ]  
  [ x x x x x x ]  
  [ x x         ]  
  </code></pre>
  
  <p>Here is what the desired layout looks like:  </p>
  
  <pre><code>[ x x x x x ]  
  [ x x x x x ]  
  [    x x    ]  
  </code></pre>