me design LevelViewController (TableView) -> present -> GameViewController . SKView . Scene
When I dismiss the GameViewController, the scene “update” (onEnterFrame) still running, to prove that the scene has not been killed
And after several time present the GameViewController, the app will lag becoz too many SKScene is running.
(self.view as! SKView).presentScene(nil) when GameViewController
self.dismissViewControllerAnimated(true, completion: nil)