Question

所以我环顾四周，我无法找到我做错的事情，我正在运行Swift 1.2，顺便使用SpriteKit。

//showing you just in case
import SpriteKit

//My variables
var countDownLabel = SKLabelNode(fontNamed: "AmericanTypewriter-Light")
var time = 4
var timer = NSTimer()

//Don't want to give you my entire project, I know I can't override a function outside of its class 
override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) { 
    for touch in (touches as! Set<UITouch>) {
        let location = touch.locationInNode(self)

        if playButton.containsPoint(location) {

//I want this to run 4 times, but is only running once
            func countdown() {
                time--
                    countDownLabel.text = "\(time)"
            }       

//This is set to run my function every second for ever.
         timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector(countdown()), userInfo: nil, repeats: true)

            playButton.removeFromParent()

            countDownLabel.fontColor = SKColor.blackColor()
            countDownLabel.fontSize = 70
            self.addChild(countDownLabel)   
        }  
    }

我希望我的函数倒计时运行4次，但它只运行一次由于某种原因，即使它设置为永远运行，我也没有收到任何错误或警告，对不起，如果显而易见，如果代码很难理解，我只是包含了它所有的功能。

Answer 1

＆＃39;选择器（倒计时（））＆＃39;被评估为零。所以，

1.Move＆＃39;倒计时＆＃39;功能到touchesBegin之外。

2.使用选择器：＆＃34;倒计时＆＃34;＆＃39;而不是＆＃39;选择器（倒计时（））＆＃39;

3.调用四次后使计时器失效。

var time = 4
var timer = NSTimer()

func countdown() {
    if --time == 0 { timer.invalidate() }
    println( "\(time)" )
}       

func X() {
    timer = NSTimer.scheduledTimerWithTimeInterval( 1, target: self, selector: "countdown", userInfo: nil, repeats: true)
}

Swift NSTimer只运行一次函数

1 个答案: