Continue countdown timer when app is running in background/suspended

Question

I have a functional countdown timer.

The problem is that I need to continue the countdown when the user puts the app in the background. Or suspends the app? I am no

Answer 1

Try this instead.. this code updates the time when app comes back from background/suspend and in active state..

class ProgressV: UIView {

var timer: NSTimer!
var expirationDate = NSDate()

//Set the time that you want to decrease..
var numSeconds: NSTimeInterval = 36000.0 // Ex:10:00 hrs

func startTimer()
{
    // then set time interval to expirationDate…
    expirationDate = NSDate(timeIntervalSinceNow: numSeconds)
    timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: #selector(updateUI(_:)), userInfo: nil, repeats: true)
    NSRunLoop.currentRunLoop().addTimer(timer, forMode: NSRunLoopCommonModes)

}
func updateUI(timer: NSTimer)
{
  // Call the currentTimeString method which can decrease the time..
   let timeString = currentTimeString()
   labelName.text = timeString
}
func currentTimeString() -> String {
    let unitFlags: NSCalendarUnit = [.Hour, .Minute, .Second]
    let countdown: NSDateComponents = NSCalendar.currentCalendar().components(unitFlags, fromDate: NSDate(), toDate: expirationDate, options: [])

    var timeRemaining: String
    if countdown.hour > 0
    {
        timeRemaining = String(format: "%02d:%02d:%02d", countdown.hour, countdown.minute, countdown.second)
    }
    else {
        timeRemaining = String(format: "%02d:%02d:%02d", countdown.hour, countdown.minute, countdown.second)
    }
    return timeRemaining
}

}