ios - Swift:在 touchesBegan 中使用 switch 语句

Question

我想在 SKScene 中清理我的 touchesBegan(..)。我想做一个 case 语句而不是我的 if .. else 链。但是，我在实现时遇到错误，这表明我不知道幕后是如何实现平等的。

代码之前:

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    for touch: AnyObject in touches {
        let location = touch.locationInNode(self)

        if self.nodeAtPoint(location) === playLabel {
            buildLevelSelect()
        } else if self.nodeAtPoint(location) === aboutLabel {
            createAboutView()
        } else if self.nodeAtPoint(location) === storeLabel {
            createStore()
        }
    }
}

代码后:点击后，一些标签点击有效，但其他一些标签引发Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode 0x0)错误:

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    for touch: AnyObject in touches {
        let location = touch.locationInNode(self)

        switch(self.nodeAtPoint(location)){
        case playLabel :
            buildLevelSelect()
        case aboutLabel :
            createAboutView()
        case storeLabel :
            createStore()
        default : break
    }
}

Answer 1

如果您希望 === 行为如下，您可以编写一种看起来很奇怪但功能正常的 switch:

switch(true){
        case self.nodeAtPoint(location) === playLabel : buildLevelSelect()
        case self.nodeAtPoint(location) === aboutLabel : createAboutView()
        case self.nodeAtPoint(location) === storeLabel : createStore()
        default : break
}

在我看来，这仍然比 if-else 链看起来更干净。