我可以使 SKSpriteNode 上的初始化失败而不会使应用程序崩溃吗？

Question

我正在通过 for 循环遍历下面的代码。如果某些情况属实，我想“不”创建 SKSpriteNode。是否有特定的 return，即 -1，我可以调用它来导致 SKSpriteNode 不被创建，而不会使应用程序崩溃？

或者这是我在创建它之前需要弄清楚的事情吗？

class GuessSlot : SKSpriteNode{
    var nodeIndex : Int
    var holdingGem : Bool = false

    init(color: SKColor, size: CGSize, width: CGFloat, iFactor: Int, guessBarRef: GuessBar){
        let skTexture = SKTexture(imageNamed: "gem_slot")
        self.nodeIndex = iFactor
        super.init(texture: skTexture, color: color, size: size)
        self.name = "slot"
        self.size.width     = size.width
        self.size.height    = size.width
        self.anchorPoint    = CGPoint(x: 0.5, y: 0.5)
        var indexSpacing    = (size.width * CGFloat(iFactor)) +
            ((size.height * 2) * CGFloat(iFactor)) + (size.width/2)
            indexSpacing += 10

        self.position = CGPoint(x: indexSpacing, y: guessBarRef.size.height/2)

        self.isHidden = false
        guessBarRef.addChild(self)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
 }

Answer 1

看来您可能想要 failable initializer。这将 return nil（意思是“无”，有点像 -1）。

init?(color: SKColor, size: CGSize, width: CGFloat, iFactor: Int, guessBarRef: GuessBar) {
    if /* your condition here */ {
        return nil
    }
}

然后您可以像这样使用它：

if let slot = GuessSlot(color: ..., size: ..., width: ..., iFactor: ..., guessBarRef: ...) {
    /// `SKSpriteNode` has been created
} else {
    /// won't crash app and `SKSpriteNode` is not created
}

我可以使 SKSpriteNode 上的初始化失败而不会使应用程序崩溃吗？

Can I make init on SKSpriteNode fail without crashing the app?

swift

skspritenode