title: removeFromSuperview doesn't work for UIView's added to SKScene
body: <p>I am adding a UIView to the view of an SKScene.  Later, when I wish to remove that UIView form its superview, using the standard method of uiview.removeFromSuperview does not seem to work. How should I be accomplishing this instead?  Here is how I add the UIView:</p>
  
  <pre><code>func addContainerView() {
  
      let containerRect = CGRectMake(400, 24, 600, 720)
      smallerView = UIView(frame: containerRect)
      smallerView.backgroundColor = UIColor.redColor()
      self.view.addSubview(smallerView)
  }
  </code></pre>
  
  <p>Here is how I am attempting to remove it:</p>
  
  <pre><code>func removeContainerView() {
  
      smallerView.removeFromSuperview()
  }
  </code></pre>
  
  <p>This all takes place within the SKScene class, so here 'self' refers to that scene.
  Any thoughts?</p>