更改滚动速度

Question

 var speed: CGFloat = 5

 override func didMoveToView(view: SKView) {
        /* Setup your scene here */

 var move = SKAction.moveTo(CGPoint(x: node.position.x, y: -(self.frame.height)), duration: NSTimeInterval(speed))
 var reset = SKAction.moveTo(CGPoint(x: node.position.x, y: self.frame.height ), duration: 0)

        var scroll = SKAction.sequence([move, reset])
        node.runAction(SKAction.repeatActionForever(scroll))
    }



    override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
        /* Called when a touch begins */

        for touch: AnyObject in touches {
            let location = touch.locationInNode(self)

    speed++
     println(speed)
}

我有一个想要滚动的节点，我希望它的速度根据玩家的触摸而变化，我的问题是当玩家触摸时值确实增加但节点本身保持相同的初始值。我也试过更改更新方法，但也没有。 怎么解决这个问题？