title: UICollectionView custom cell layout
body: <p>I have a UICollectionView and I'm trying customize it a little.</p>
  
  <p>Here's what I want:
  <a href="https://i.stack.imgur.com/rPtiv.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rPtiv.png" alt="enter image description here"></a></p>
  
  <p>Here's what I have:
  <a href="https://i.stack.imgur.com/3xflU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3xflU.png" alt="enter image description here"></a></p>
  
  <p>I thought implementing sizeForItemAtIndexPath from UICollectionViewDelegate would be enough. </p>
  
  <p>Here's what I'm doing:
  - I returning half of the screen's width for all the cell's widths
  - For the first and third cells I'm returning a height of 50
  - For the second cell I'm returning a height of 100.</p>
  
  <p>What am I doing wrong? </p>