title: How to enable zoom for UICollectionView
body: <p>I am confused. I have a <code>UICollectionView</code>. I have my own <code>UICollectionViewLayout</code> subclass (iow, I am not using the Flow thing). <code>UICollectionView</code> instance is a subclass of <code>UIScrollView</code>. It adds multiple subviews. But questions like <a href="https://stackoverflow.com/questions/1835941/properly-zooming-a-uiscrollview-that-contains-many-subviews">Properly zooming a UIScrollView that contains many subviews</a> seem to say that scrollable views should just have one subview to "scroll the whole view". Seems kind of an inconsistent marriage to me. I mean why does Apple give me a framework for making a multiple child view, and then stick them all in scroll view, which isn't supposed to work well?</p>
  
  <p>So I'm curious how I should go about making my whole <code>UICollectionView</code> (it's in a <code>UICollectionViewController</code> subclass) zoomable. Do I need to implement various delegate methods and invalidate/manipulate the layout object, deriving the layouts based on some property I keep in my layout? Or is there some other mechanism?</p>
  
  <p>Aside, why can't it just manipulate the <code>zoomScale</code> property and do it automagically for me? Or am I missing some subtlety here?</p>