Xcode swift中的“func TouchesBegind”错误

好吧，我还在学习swift，我正在玩的游戏有一个崩溃错误，当我触摸屏幕使地面移动时，应用程序崩溃。错误显示为绿色，表示致命错误：在展开可选值时意外发现零错误显示在GameSecene.swift的第27行靠近底部这是GameSecene代码

import SpriteKit


class GameScene: SKScene {

 var movingGround: AWMovingGround!

  override func didMoveToView(view: SKView) {
    backgroundColor = UIColor.blueColor()

    let movingGround = AWMovingGround (size: CGSizeMake(view.frame.width,20 ))
    movingGround.position = CGPointMake( 0, view.frame.size.height/2)
    addChild(movingGround)

}

**ERROR HIGHLIGHTS "movingGround.start()"**
override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
    movingGround.start()

}

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

这是移动地面和移动地面的代码

import Foundation
import SpriteKit

class AWMovingGround: SKSpriteNode {

let NUMBER_OF_SEGMENTS = 20
let COLOR_ONE = UIColor.greenColor()
let COLOR_TWO = UIColor.brownColor()

init (size: CGSize){
    super.init(texture: nil , color: UIColor.redColor(), size: CGSizeMake(size.width*2, size.height))
    anchorPoint = CGPointMake(0,0.5)
    for var i = 0; i < NUMBER_OF_SEGMENTS; i++ {
        var segmentColor = UIColor()
        if i % 2 == 0{
            segmentColor = COLOR_ONE
        }else{
            segmentColor = COLOR_TWO
        }
        let segment = SKSpriteNode(color: segmentColor, size: CGSizeMake(self.size.width / CGFloat(NUMBER_OF_SEGMENTS), self.size.height))
        segment.anchorPoint = CGPointMake(0, 0.5)
        segment.position = CGPointMake(CGFloat(i)*segment.size.width, 0)
        addChild(segment)


    }

}
required init?(coder aDecoder:NSCoder){
    fatalError(" init(coder:) has not been implimented")

}

 func start(){
    let moveleft = SKAction.moveByX(-frame.size.width/2, y: 0,          duration: 1.0)
    runAction(moveleft, completion: nil)
}
}

就在这里

你宣布地面移动

var movingGround: AWMovingGround!

但决不要分配给它，而是创建一个本地范围和同名的版本，这是合法和有效的语法

override func didMoveToView(view: SKView) {
...
let movingGround = AWMovingGround (size: CGSizeMake(view.frame.width,20 ))
...
}

所以你想要的是

var movingGround: AWMovingGround!

  override func didMoveToView(view: SKView) {
    backgroundColor = UIColor.blueColor()

    movingGround = AWMovingGround (size: CGSizeMake(view.frame.width,20 ))
    movingGround.position = CGPointMake( 0, view.frame.size.height/2)
    addChild(movingGround)

}

---

你是从哪里来的？天哪，非常感谢你，我一直在努力解决这个问题很长时间了