swiftでYMCPhysicsDebuggerが使えなかった話（showsPhysicsを使おう） ref: http://qiita.com/suisho/items/81ec4aa3e197086bb3ab

file0.swift

class GameViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        if let scene = GameScene.unarchiveFromFile("GameScene") as? GameScene {

            // Configure the view.
            let skView = self.view as! SKView
            skView.showsFPS = true
            skView.showsNodeCount = true

            skView.ignoresSiblingOrder = true
            skView.showsPhysics = true // これ
            scene.scaleMode = .AspectFit

            skView.presentScene(scene)
        }
    }

}