title: EXC_BAD_INSTRUCTION bug
body: <p>I have gotten this problem several times in Xcode 6. the thing is that I got a ball running and when he hits a block he dies. he can jump though. but the very first block always crashes. like if I just roll normally like not in the air and hit the first block it just freezes and closes.</p>
  
  <p>It gives me this error:</p>
  
  <blockquote>
    <p>Thread 1: EXC_BAD_INSTRUCTION(code=EXC_1386_INVOP, subcode=0x0)</p>
  </blockquote>
  
  <p>Line number 2 and 7 have a green background (counting the space).</p>
  
  <p>This is the error line: </p>
  
  <pre><code>func didBeginContact(contact:SKPhysicsContact) {
      died()
  }
  
  func died() {
      if let scene = GameScene.unarchiveFromFile("GameScene") as? GameScene { 
          let skView = self.view as SKView                                                                
          skView.ignoresSiblingOrder = true
          scene.size = skView.bounds.size
          scene.scaleMode = .AspectFill
          skView.presentScene(scene)
      }
  }
  </code></pre>