title: SpriteKit how to get correct screen size
body: <p>I've tried </p>
  
  <pre><code>self.frame.size
  self.view!.frame.size
  UIScreen.mainScreen().bounds.size
  </code></pre>
  
  <p>None of them work.</p>
  
  <p>How do I get the correct screen size for the device?</p>