title: CollectionView crashes after HOME button pressed on iPads
body: <p>I have a CollectionView and I set size for its cells dynamically. Here is the problem: when I hit 'home' button and enter the game again, then the CollectionView cracks. All the cell look awful, they have wrong size and appears in wrong place. And it happens only on iPads and works perfectly on iPhones.
  Here is my code for creating the table:</p>
  
  <pre><code>if collectionView == tableCollectionView{
  
          let cell:TableViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: "letter_cell", for: indexPath) as! TableViewCell
  
          let size = Int(collectionView.frame.size.width) / (lettersCountInRow + 1);
          let j = indexPath.row
          let i = indexPath.section
  
          let letter = guessLogic!.letters[i * lettersCountInRow + j]
          let imageName = String(describing: letter)
  
          let vertical_shift = (Int(collectionView.frame.size.height) - size * 2) / 2
          let pad = Double(size) * 0.1;
          let start_x = Int(collectionView.frame.size.width) - size*7 - Int(pad) * lettersCountInRow;
  
  
          cell.letterImage.image = UIImage(named: imageName)
          cell.frame = CGRect(x:start_x + j * Int(pad) + j * size, y: i * size + vertical_shift + Int(pad), width: size, height: size)
  
          return cell
  
      }
  </code></pre>
  
  <p>Tested on iPad Air-2</p>
  
  <p>This is how the table always should looks like:
  <a href="http://imgh.us/air-2.png" rel="nofollow noreferrer">Normal look</a></p>
  
  <p>And this how it looks like after I press HOME and return to the game:
  <a href="http://imgh.us/air-2_wrong.png" rel="nofollow noreferrer">Wrong bullsh*t look</a></p>