Xcode Swift 秒表应用

Question

我正在制作一个秒表应用程序，目前在 UILabel 上显示分钟、秒和毫秒。它有一个 'Start' 按钮和一个 'Stop' 按钮。代码如下。如何添加小时数？另外，当我停止它时，如何让它继续它原来的位置？目前，如果我再次按下开始，它会重置并重新开始。稍后我会添加一个重置按钮。

//Variables
var startTime = NSTimeInterval()

//Start Button
@IBAction func start(sender: AnyObject) {
   let aSelector : Selector = “updateTime”
   timer = NSTimer.scheduledTimerWithTimeInterval(0.01, target: self, selector: aSelector, userInfo: nil, repeats: true)
   startTime = NSDate.timeIntervalSinceReferenceDate()
}

//Stop Button
@IBAction func stop(sender: AnyObject) {
   timer.invalidate()
}

//Update Time Function
func updateTime() {

   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 = UInt8(elapsedTime / 60.0)

   elapsedTime -= (NSTimeInterval(minutes) * 60)

   //calculate the seconds in elapsed time.

   let seconds = UInt8(elapsedTime)

   elapsedTime -= NSTimeInterval(seconds)

   //find out the fraction of milliseconds to be displayed.

   let fraction = UInt8(elapsedTime * 100)

   //add the leading zero for minutes, seconds and millseconds and store them as string constants

   let strMinutes = String(format: "%02d", minutes)
   let strSeconds = String(format: "%02d", seconds)
   let strFraction = String(format: "%02d", fraction)

   //concatenate minuets, seconds and milliseconds as assign it to the UILabel

   displayTimeLabel.text = “\(strMinutes):\(strSeconds):\(strFraction)”

}

Answer 1

你可以这样计算小时

elapsedtime / 3600

阅读更多NSTimeInterval to HH:mm:ss?

Answer 2

要继续在秒表上计数：

创建var stopTime : NSTimeInterval = 0

调用 stop() 函数时，插入此代码：

 stopTime = elapsedTime

在 start() 函数中，替换为：

elapsedTime = (currentTime - startTime) + stopTime

或者你可以使用NSDate(), NSDateFormatter()来解决这个问题。参考这里enter link description here

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