Swift Sprite Kit开始触摸功能

我正在搞乱一个 xcode项目,当我触摸它时,我正试图让一个红色的球SKShapeNode四处移动.触摸我自己的源代码开始上课并没有做到.我的代码有什么缺陷,我需要做些什么来修复它.

import SpriteKit

class GameScene: SKScene {

    //Rectangle Skeletions
    var leftWallRect = CGRect(x: 0,y: 0,width: 40,height: 1000)

    var ball = SKShapeNode(circLeofRadius: 25);


    override func didMoveToView(view: SKView) {

        // Declare the Sprites in your scene
        var ball = SKShapeNode(circLeofRadius: 25);
        let leftWall = SKShapeNode(rect: leftWallRect);
        let rightWall = SKShapeNode(rect: leftWallRect);
        let pin = SKSpriteNode(imagenamed: "pin");

        // Ball Properties
        ball.strokeColor = UIColor.blackColor()
        ball.fillColor = UIColor.redColor()
        ball.position = CGPointMake(self.frame.width / 2,self.frame.height / 4 - 100 )
        self.addChild(ball)

        // Left Wall Properties
        leftWall.fillColor = UIColor.purpleColor()
        leftWall.strokeColor = UIColor.blackColor()
        leftWall.position = CGPointMake(self.frame.size.width / 3 - 45,self.frame.size.height / 2 - 400)
        self.addChild(leftWall)

        //Right Wall Properties
        rightWall.fillColor = UIColor.purpleColor()
        rightWall.strokeColor = UIColor.blackColor()
        rightWall.position = CGPointMake(self.frame.size.width / 2 + 175,self.frame.size.height / 2 - 400)
        self.addChild(rightWall)
    }

    override func touchesBegan(touches: Set<NSObject>,withEvent event: UIEvent) {
        /* Called when a touch begins */

        let touch = touches.first as! UITouch
        let touchLOCATIOn = touch.LOCATIOnInNode(self)

        if touchLOCATIOn == ball.position{

            ball.position = touchLOCATIOn

            println("Touches");
        }
    }

    override func update(currentTime: CFTimeInterval) {
        /* Called before each frame is rendered */
    }
}

let touch = touches.first as! UITouch
let touchLOCATIOn = touch.LOCATIOnInNode(self)
let touchedNode = self.nodeAtPoint(touchLOCATIOn)
if touchedNode == ball{
...