title: UICollectionView not the right size in viewDidLoad
body: <p>I have a simple UICollectionView defined in my storyboard (see screenshot).</p>
  
  <p><a href="https://i.stack.imgur.com/uZAVW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uZAVW.png" alt="enter image description here"></a></p>
  
  <p>I'm using auto layout, the UICollectionView is attached to the superview for leading, trailing and top and to the toolbar for the bottom.</p>
  
  <p>When I display in the console the size of the UICollectionView in viewDidLoad with:</p>
  
  <pre><code>NSLog(@"%s CollectionView ========== &gt; height:%f width:%f", __PRETTY_FUNCTION__,self.theCollectionView.bounds.size.height, self.theCollectionView.bounds.size.width);
  </code></pre>
  
  <p>I get:
  CollectionView ========== > Frame height:492.000000 width:600.000000</p>
  
  <p>This size is the one which is also displayed in the storyboard (Width:600 Height:492).</p>
  
  <p>When I run the same log in viewDidAppear, I get:
  CollectionView ========== > Frame height:663.000000 width:1024.000000</p>
  
  <p>which is what I expect. I'm surprise to have the appropriate size only in the viewDidAppear, please can you explain or is there something wrong in my storyboard?</p>
  
  <p>Thanks,</p>
  
  <p>Sébastien.</p>