How to get user interaction events in playground with Swift

I'm trying to prototype a game with `SpriteKit` with `Swift` in a `playground`. I'm having difficulties getting the user touch callbacks to work. Here's what I am trying : ``` let view:SKView = SKView(frame: CGRectMake(0, 0, 320, 586)) XCPShowView("Live view", view) class PrototypeScene: SKScene { override func didMoveToView(view: SKView) { self.userInteractionEnabled = true } override func touchesBeganWithEvent(event: NSEvent!) { println("Hello touches") } } let scene:PrototypeScene = PrototypeScene(size: CGSizeMake(320, 586)) scene.scaleMode = SKSceneScaleMode.AspectFit view.presentScene(scene) ``` I'm not getting the callbacks for the responder chain. How would one enable this?