无法识别的选择器发送到实例NSTimer Swift

Question

我正在尝试开发一个包含简单秒表功能的应用程序.我正在使用Xcode 6和Swift语言.这是FirstViewController中的代码

@IBAction func Stopwatch (Sender:UIButton) { 

var startTime = NSTimeInterval()

    func updateTime(timer:NSTimer) {

        //Find Current TIme

        var currentTime = NSDate.timeIntervalSinceReferenceDate()

        //Find the difference between current time and start time

        var elapsedTime :NSTimeInterval = currentTime - startTime

        //calculate the minutes in elapsed time.
        let minutes = UInt(elapsedTime / 60.0)
        elapsedTime -= (NSTimeInterval(minutes) * 60)

        //calculate the seconds in elapsed time.
        let seconds = UInt(elapsedTime)
        elapsedTime -= NSTimeInterval(seconds)

        //find out the fraction of milliseconds to be displayed.
        let hours = UInt(elapsedTime * 100)

        let strMinutes = minutes > 9 ? String(minutes):String(minutes)
        let strSeconds = seconds > 9 ? String(seconds):String(seconds)
        let strHours = hours > 9 ? String(hours):String(hours)

        //assign text to Label
        elapsedTimeLabel.text = "You have slept for \(strHours)"
    }

    //Timer 
    var timer = NSTimer.scheduledTimerWithTimeInterval(0.5, target: self, selector: Selector("updateTime:"), userInfo: nil, repeats: true)
    startTime = NSDate.timeIntervalSinceReferenceDate()

}
}

每次我运行应用程序(在iOS模拟器中)时,按下按钮时应用程序崩溃(执行秒表功能).错误总是读取

2014-11-23 11:44:53.617 Sleep[9630:644637] -[Sleep.FirstViewController updateTime:]: 
unrecognized selector sent to instance 0x7ff6d9676e80
2014-11-23 11:44:53.622 Sleep[9630:644637] *** Terminating app due to uncaught exception 
'NSInvalidArgumentException', reason: '-[Sleep.FirstViewController updateTime:]: unrecognized 
selector sent to instance 0x7ff6d9676e80'
*** First throw call stack:

我不知道为什么会这样,我对iOS编程很新,所以请帮忙!

Answer 1

让updateTime成为一个类方法.
如果它是一个纯粹的Swift类,你需要在@objc前面说明该方法的声明,如:

class A {
     @objc func updateTime(timer:NSTimer) {

     }
}

Answer 2

您已将 定义updateTime为 的本地函数Stopwatch，因此它在其范围之外不可用。您应该将其移动到类级别（与 相同Stopwatch）以便可以访问。

然而我注意到有一些局部变量可能应该是实例属性。