title: Issue with background in collection view
body: <p>So I'm creating a collection view, where on the scroll of each cell the collection view background changes to a image I have. The issue is the bg changes before the cell is even in the view. How do I fix this?</p>
  
  <pre><code>func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -&gt; UICollectionViewCell {
      let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath) as! HomeCollectionViewCell
      cell.cellNavTitle.text = appConfig.menuItems[indexPath.row]
      cell.cellNavImage.image = UIImage(named: (appConfig.icon[indexPath.row]))
      cell.cellNavDescription.text = appConfig.title[indexPath.row]
  
      switch indexPath.row{
      case 0:
        collectionView.backgroundColor = UIColor(patternImage: UIImage(named: "1414441938milaj_bg2")!)
        break
      case 1:
        collectionView.backgroundColor = UIColor.blueColor()
        break
      case 2:
        collectionView.backgroundColor = UIColor.grayColor()
        break
      default:
        break
      }
  
      return cell       
  }
  </code></pre>