title: how to make dynamic width of the UICollectionViewCell
body: <p>I want to set the width of <code>UICollectionViewCell</code> dynamically.
  I found some code in swift and I want the code in Objective-C.</p>
  
  <pre><code>let flowLayout = collectionViewLayout as! UICollectionViewFlowLayout
      if indexPath.item % 3 == 0 {
          let cellWidth = (CGRectGetWidth(collectionView.frame) - (flowLayout.sectionInset.left + flowLayout.sectionInset.right))
          return CGSize(width: cellWidth, height: cellWidth / 2)
      } else {
          let cellWidth = (CGRectGetWidth(collectionView.frame) - (flowLayout.sectionInset.left + flowLayout.sectionInset.right) - flowLayout.minimumInteritemSpacing) / 2
          return CGSize(width: cellWidth, height: cellWidth)
      }
  </code></pre>