title: when using subclassed collectionViewFlowLayout I'm getting weird error
body: <p>I made a subclass of <code>collectionViewFlowLayout</code>. After that, I implemented the following code:</p>
  
  <pre><code>override func finalLayoutAttributesForDisappearingItemAtIndexPath(itemIndexPath: NSIndexPath) -&gt; UICollectionViewLayoutAttributes? {
          let attr = self.layoutAttributesForItemAtIndexPath(itemIndexPath)
          attr?.transform = CGAffineTransformRotate(CGAffineTransformMakeScale(0.8, 0.8), CGFloat(M_PI))
          attr?.center = CGPointMake(CGRectGetMidX(self.collectionView!.bounds), CGRectGetMidY(self.collectionView!.bounds))
          return attr
      }
  </code></pre>
  
  <p>When I delete items in collection view using <code>performBatchUpdates</code>: method the debugger throws this error message. The deletion actually succeeds and is fully working, but I am a little confused about this debugger output. Can someone please explain should I do to please debugger? I don't really understand what code and where should be added.</p>
  
  <p>//ERROR MESSAGE</p>
  
  <blockquote>
    <p>2015-08-02 12:39:42.208 nameOfMyProject[1888:51831] Logging only once
    for UICollectionViewFlowLayout cache mismatched frame 2015-08-02
    12:39:42.209 nameOfMyProject[1888:51831] UICollectionViewFlowLayout
    has cached frame mismatch for index path  {length = 2, path = 0 - 11} - cached value:
    {{106.13333333333333, 131.13333333333333}, {75.733333333333348,
    75.733333333333348}}; expected value: {{192.5, 288}, {94.666666666666671, 94.666666666666671}}</p>
    
    <p>2015-08-02 12:39:42.209 nameOfMyProject[1888:51831] This is likely
    occurring because the flow layout subclass nameOfMyProject.ShopLayout
    is modifying attributes returned by UICollectionViewFlowLayout without
    copying them</p>
    
    <p>2015-08-02 12:39:42.209 nameOfMyProject[1888:51831] Snapshotting a
    view that has not been rendered results in an empty snapshot. Ensure
    your view has been rendered at least once before snapshotting or
    snapshot after screen updates.</p>
  </blockquote>