Question

我的下面的代码有问题，我非常需要我按下的节点名称的最后一个字母。

为此，我迭代了场景中的所有子节点，直到找到一个与触摸点共享位置的子节点。

一旦发现这一点，我就会使用警卫声明：

let nodeName = node.name
            guard let letter = nodeName?.last else { return }

查找字母，但是编译器在尝试从节点名称中提取最后一个字符时找不到nil，因此不会继续运行这些函数。

非常感谢我和我作为初学者对我和我的代码的耐心

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {

    guard let touch = touches.first else { return }
    let touchPosition = touch.location(in: self)
    guard let scene = scene else { return }

    for node in scene.children {
        if node.frame.contains(touchPosition) && node.name != "background" {
            let nodeName = node.name
            guard let letter = nodeName?.last else { return }
            handleGuess(letter: letter)
            node.removeFromParent()
            if !(lettersToGuess?.contains(letter))! && letter != "1" && letter != "0" {
                currentStep += 1
            } else if letter == "1" {

            } else if letter == "2" {

            } else if letter == "3" {

            } else if letter == "4" {

            }
        }
    }
}

func setupMenu() {      
    // Load Background and place background image
    let backgroundTexture = SKTexture(imageNamed: "menuBG")
    background.texture = backgroundTexture
    background.zPosition = -1
    background.position = CGPoint(x: frame.midX * 0.25, y: frame.midY)
    let bgSizeFactor = backgroundTexture.size().height / frame.size.height
    background.size = CGSize(width: backgroundTexture.size().width / bgSizeFactor , height: frame.size.height)
    addChild(background)

    animateBackground()
    setupRain()

    // TODO: Add Button center screen displaying current level, clicking this will start a new game.
    let playTexture = SKTexture(imageNamed: "playButton")
    let playButton = SKSpriteNode(texture: playTexture)
    playButton.name = "playbutton2"
    let playButtonFactor = playTexture.size().width / frame.size.width
    playButton.size = CGSize(width: frame.size.width * 0.65, height: (playTexture.size().height / playButtonFactor) * 0.65)
    playButton.position = CGPoint(x: frame.midX, y: frame.midY)
    playButton.zPosition = 1
    addChild(playButton)

    let rateTexture = SKTexture(imageNamed: "rateButton")
    let rateButton = SKSpriteNode(texture: rateTexture)
    rateButton.name = "rateButton3"
    rateButton.size = CGSize(width: playButton.size.height * 0.85, height: playButton.size.height * 0.85)
    rateButton.position = CGPoint(x: frame.midX, y: frame.midY - playButton.size.height)
    rateButton.zPosition = 1
    addChild(rateButton)

    let noAdsTexture = SKTexture(imageNamed: "noAdsButton")
    let noAdsButton = SKSpriteNode(texture: noAdsTexture)
    noAdsButton.name = "noAdsButton4"
    noAdsButton.size = CGSize(width: playButton.size.height * 0.85, height: playButton.size.height * 0.85)
    noAdsButton.position = CGPoint(x: frame.midX - playButton.size.height, y: frame.midY - playButton.size.height)
    noAdsButton.zPosition = 1
    addChild(noAdsButton)

    let zapTexture = SKTexture(imageNamed: "zapButton")
    let zapButton = SKSpriteNode(texture: zapTexture)
    zapButton.name = "zapButton5"
    zapButton.size = CGSize(width: playButton.size.height * 0.85, height: playButton.size.height * 0.85)
    zapButton.position = CGPoint(x: frame.midX + playButton.size.height, y: frame.midY - playButton.size.height)
    zapButton.zPosition = 1
    addChild(zapButton)
}

Answer 1

我认为您的下一行是问题

guard let letter = nodeName?.last else { return }

您将返回此处，这会中断for循环并从方法中返回。而是尝试将其替换为下面的内容。

guard let letter = nodeName?.last else { continue }

如果当前节点的字母为nil，则以上将继续循环。

解开node.name.last（）时找到nil

1 个答案: