Question

我是ios和swift的新手但不幸的是我无法弄清楚如何计算倒数计时器。我做了什么？ .it是完全的，如果我从当前机器时间设置。但不会打扮时间。我知道它应该不起作用。但我不知道我怎么能让它工作。谢谢

 // MARK:- Timer

    let startFormatter = NSDateFormatter()
    let endFormatter = NSDateFormatter()
    let userClander = NSCalendar.currentCalendar()

    let requestComponent: NSCalendarUnit = [
        NSCalendarUnit.Month,
        NSCalendarUnit.Day,
        NSCalendarUnit.Hour,
        NSCalendarUnit.Minute,
        NSCalendarUnit.Second

    ]

    func printTime(){
        //let startTime = NSDate()

        startFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
        endFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"

        let requestTimeString = "2017-01-16 12:55:27"
        let requestTime = startFormatter.dateFromString(requestTimeString)

        let endTimeString = "2017-01-16 12:58:27"
        let endTime = endFormatter.dateFromString(endTimeString)


         print(endTime)

        let timeDifferance = userClander.components(requestComponent, fromDate: requestTime!, toDate: endTime!, options: [])

        print(timeDifferance.minute)


        displayCountDownTimerLabel.text = "\(timeDifferance.minute):\(timeDifferance.second)"

    }

    func start() {

        let timer = NSTimer.scheduledTimerWithTimeInterval(0.01, target: self, selector: #selector(ViewController.printTime), userInfo: nil, repeats: true)
        timer.fire()
    }

Answer 1

 let aSelector : Selector  = #selector(updateTime)

        timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: aSelector, userInfo: labelCalIndex, repeats: true)

func updateTime()
{
   let currentTime = NSDate.timeIntervalSinceReferenceDate()
        /* ----------------------------------------------------------------

                Find the difference between current time and start time.

         ---------------------------------------------------------------- */

        var elapsedTime: NSTimeInterval = currentTime - startTime

        /* ------------------------------------------------

                calculate the hours in elapsed time.

           ------------------------------------------------ */

        let hour = Int32( elapsedTime / 3600.0 )

        elapsedTime -= (NSTimeInterval(hour) * 3600)
        /* ------------------------------------------------

                calculate the minutes in elapsed time.

           ------------------------------------------------ */

        let minutes = Int32(elapsedTime / 60.0)

        elapsedTime -= (NSTimeInterval(minutes) * 60)

        /* ------------------------------------------------

                calculate the seconds in elapsed time.

           ------------------------------------------------ */

        let seconds = Int32(elapsedTime)

        elapsedTime -= NSTimeInterval(seconds)

        /* ------------------------------------------------------------------------------------------------------

                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 strHour = String(format: "%02d", hour)

        /* -------------------------------------------------------------------------------------------

                Concatenate minuets, seconds and milliseconds as assign it to the UILabel

           ------------------------------------------------------------------------------------------- */

        let timerSting = "\(strHour):\(strMinutes):\(strSeconds)"

        if minutes == 3 
        {
             InvalidateTimer()

        }
    }

将您的开始时间保存在NSInterval中。

Answer 2

如果您想要在指定的持续时间内使用3分钟计时器或计时器，则无需使用NSDate。

Swift 3

如果你想要一个3分钟的计时器：

@IBOutlet weak var timerLabel: UILabel!

var currentTime : Int!

var timer : Timer!

override func viewDidLoad() {

    super.viewDidLoad()

    //total time in seconds.
    currentTime = 180

    timerLabel.text = convertSecondsToMinutes(currentTime)

    timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(updateLabel), userInfo: nil, repeats: true)
}

func updateLabel(){

    currentTime = currentTime - 1

    timerLabel.text = convertSecondsToMinutes(currentTime)

    //0 seconds left so kill the timer
    if(currentTime == 0){

        timer.invalidate()
    }
}

func convertSecondsToMinutes(_ seconds:Int) -> String{

    //one minute has 60 seconds soo :D

    let minutes = seconds/60

    let secondsvalue = Double(seconds).truncatingRemainder(dividingBy: 60)

    //return string in appropriate format
    return "\(minutes):\(Int(secondsvalue))"
}

Answer 3

// MARK： - 定时器

let startFormatter = NSDateFormatter()
let endFormatter = NSDateFormatter()
let userClander = NSCalendar.currentCalendar()

let requestComponent: NSCalendarUnit = [
    NSCalendarUnit.Month,
    NSCalendarUnit.Day,
    NSCalendarUnit.Hour,
    NSCalendarUnit.Minute,
    NSCalendarUnit.Second

]

var count = 0

func printTime(){

        if(count > 0){
            let minutes = String(count / 60)
            let seconds = String(count % 60)

            print(minutes)
            print(seconds)
            displayCountDownTimerLabel.text = minutes + ":" + seconds
            count -= 1
         }
        else{
              displayCountDownTimerLabel.text = "00:00"
         }

}

func start() {

    startFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
    endFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"

    let requestTimeString = "2017-01-16 12:58:27"
    let requestTime = startFormatter.dateFromString(requestTimeString)

    let endTimeString = "2017-01-16 12:58:56"
    let endTime = endFormatter.dateFromString(endTimeString)

    let timeDifferance = userClander.components(requestComponent, fromDate: requestTime!, toDate: endTime!, options: [])

     print("\(timeDifferance.hour):\(timeDifferance.minute):\(timeDifferance.second)")


    if timeDifferance.hour == 0 && timeDifferance.minute <= 3 {

        count = (timeDifferance.minute * 60 ) + timeDifferance.second


    let timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: #selector(ViewController.printTime), userInfo: nil, repeats: true)

    timer.fire()

    }else{
       print("request time out ")
    }
}

我无法弄清楚如何制作倒数计时器？

3 个答案: