title: Adding SKNode to SpriteKit
body: <p>I am making a game and I'm trying to add a SKNode to the GameScene, the problem is that when I run it, it crashes and displays that the problem is when I am adding the SKNode to the GameScene. Here my code.</p>
  
  <pre><code>import SpriteKit
  import GameKit
  
  class GameScene: SKScene {
     override func didMoveToView(view: SKView)
   {
        var worldsNode:SKNode = SKNode.alloc()
        self.addChild(worldsNode)  //Xcode says that here is the problem.
   }
  </code></pre>
  
  <p>What I'm doing wrong here?</p>