     
     let CATEGORY_RACKET: UInt32 = 0x00000001
     let CATEGORY_BALL: UInt32 = 0x00000010
+    let CATEGORY_ROUND: UInt32 = 0x00000100
     
     // not supported construct.
     required init(coder aDecoder: NSCoder) {

            self.sequence = .GAME
            self.drawRacket()
            self.setUiLayer()
        })
    }
    
    func didBeginContact(contact: SKPhysicsContact) {
        print("didBeginContact")
        uiLayerView!.pointup(1) // TODO fix point value.
    }
    
    override func update(currentTime: CFTimeInterval) {

        ball.physicsBody = SKPhysicsBody(circleOfRadius: width)
        ball.physicsBody?.dynamic = true
        ball.physicsBody?.categoryBitMask = CATEGORY_BALL
        ball.physicsBody?.contactTestBitMask = CATEGORY_RACKET | CATEGORY_ROUND
        self.addChild(ball)
    }
    
