swift - 调用过渡方法时，SKScene 返回 nil

Question

在我的小 Xcode 项目中，当我的 SKLabelNode 被触摸时，我试图转换场景，它会呈现下一个场景。出于某种原因，在我的场景转换方法中，它让我将其存储为可选。并且可选返回 false。我的文件名是正确的，引用中没有语法错误会导致问题，这是我的代码。当我单击我的 SKLabelNode 时，运行它的 ios 平台识别触摸然后应用程序崩溃，在控制台中说可选值返回 nil。我该如何解决这个问题？谢谢

import SpriteKit

class GameScene: SKScene {

let next = SKScene(fileNamed: "nextScene")

override func didMoveToView(view: SKView) {


    let backgroundimage = SKSpriteNode(imageNamed: "ipbg")
    backgroundimage.size = CGSize(width: self.frame.size.width, height: self.frame.size.height)
    backgroundimage.position = CGPoint(x: self.frame.size.width / 2, y: self.frame.size.height / 2)
    addChild(backgroundimage)

    let playButton = SKLabelNode(fontNamed: "")
    playButton.name = "play"
    playButton.position = CGPoint(x: self.frame.size.width / 2, y: self.frame.size.height / 2 + 100)
    playButton.text = "Play"

    let wait = SKAction.waitForDuration(2)
    let run = SKAction.runBlock({


        let randomNumber = Int(arc4random_uniform(UInt32(4)))

        switch(randomNumber){

        case (0):

            playButton.fontColor = UIColor.blueColor()

        case 1:

            playButton.fontColor = UIColor.yellowColor()

        case 2:

            playButton.fontColor = UIColor.purpleColor()

        case 3:

            playButton.fontColor = UIColor.orangeColor()

        default: print("default")


        }

    })

    addChild(playButton)
    var repeatActionForever = SKAction.repeatActionForever(SKAction.sequence([wait, run]))
    runAction(repeatActionForever)
}

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {

    let trans = SKTransition.crossFadeWithDuration(1)
    let touch = touches.first! as UITouch
    let touchLocation = touch.locationInNode(self)
    let touchedNode = nodeAtPoint(touchLocation)

    if touchedNode.name == "play"{


        scene!.view?.presentScene(next!, transition: trans)

        }

    }
}

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

Answer 1

您发布的代码无法编译，因此很难找到错误。

但是我会尝试用下面的方法替换 touchesBegan

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {

    let trans = SKTransition.crossFadeWithDuration(1)
    let touch = touches.first! as UITouch
    let touchLocation = touch.locationInNode(self)
    let touchedNode = nodeAtPoint(touchLocation)

    if touchedNode.name == "play"{
        guard let nextScene = SKScene(fileNamed: "nextScene")
            else { fatalError("Could not load nextScene") }
        self.view?.presentScene(nextScene, transition: trans)
    }
}