Swift NSTimer 将 userInfo 检索为 CGPoint

Question

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    let touch = touches.anyObject() as UITouch
    let touchLocation = touch.locationInNode(self)

    timer = NSTimer.scheduledTimerWithTimeInterval(0.5, target: self, selector: "shoot", userInfo: touchLocation, repeats: true) // error 1
}

func shoot() {
    var touchLocation: CGPoint = timer.userInfo // error 2
    println("running")
}

我正在尝试创建一个定期运行的计时器，将触摸点 (CGPoint) 作为 userInfo 传递给 NSTimer，然后在 shoot() 函数中访问它。但是，现在我收到一个错误提示

1) 调用中的额外参数选择器

2) 无法转换表达式类型 AnyObject？到CGPoint

现在我似乎无法将 userInfo 传递给其他函数然后检索它。

Answer 1

不幸的是，CGPoint 不是对象（至少在 Cocoa API 起源的 Objective-C 世界中）。它必须包装在 NSValue 对象中才能放入集合中。

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    let touch = touches.anyObject() as UITouch
    let touchLocation = touch.locationInNode(self)
    let wrappedLocation = NSValue(CGPoint: touchLocation)

    timer = NSTimer.scheduledTimerWithTimeInterval(0.5, target: self, selector: "shoot:", userInfo: ["touchLocation" : wrappedLocation], repeats: true)
}

func shoot(timer: NSTimer) {
    let userInfo = timer.userInfo as Dictionary<String, AnyObject>
    var touchLocation: CGPoint = (userInfo["touchLocation"] as NSValue).CGPointValue()
    println("running")
}