title: UICollectionViewCell align to top of each row
body: <p>I have a collection view with cells of various sizes.  I am trying to implement a general layout that would have all the cells align to the top of each row (the built in flow layout aligns all the cells to the center of the row).</p>
  
  <p>The cell with the greatest height would push all the cells down on the next row.</p>
  
  <p>Is there an easy way to subclass the layout and implement this?</p>
  
  <p>Thanks in advance for any tips.</p>