[英]Swift: Using switch statement in touchesBegan
我想在SKScene
清理我的touchesBegan(..)
。 我想創建一個case語句而不是我的if .. else
鏈。 但是,我在實現時遇到錯誤,這表明我不知道如何在引擎蓋下完成相同的操作。
代碼之前:
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()
}
}
}
代碼之后:點擊后,一些標簽點擊工作,但其他一些提出了一個Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode 0x0)
錯誤:
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
}
}
如果你想要===
行為如下所示,你可以編寫一種奇怪但功能正常的switch
:
switch(true){
case self.nodeAtPoint(location) === playLabel : buildLevelSelect()
case self.nodeAtPoint(location) === aboutLabel : createAboutView()
case self.nodeAtPoint(location) === storeLabel : createStore()
default : break
}
在我看來,這仍然比if-else鏈更清晰。
完成此操作的最簡單方法是填充節點的.name
屬性,然后您可以改為使用該名稱。 那么你的開關看起來像這樣:
switch (self.nodeAtPoint(location).name ?? "") {
case "playLabel" :
buildLevelSelect()
case "aboutLabel" :
...
您還可以在switch語句中轉換對象,然后您的代碼按預期工作
if let touch = touches.first as UITouch! {
let touchLocation = touch.location(in: self)
switch self.atPoint(touchLocation) {
case redBox as SKSpriteNode:
print("touched redBox")
case greenBox as SKSpriteNode:
print("touched greenBox")
default:
print("touched nothing")
}
}
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