Convert seconds into hours in iOS Swift? [duplicate] - ios

Question

I have a label and its value is "03:48".
I want to countdown it like a music player. How can I do that?
03:48 03:47 03:46 03:45 ... 00:00
var musictime =3:48
func stringFromTimeInterval(interval: NSTimeInterval) -> String {
let interval = Int(interval)
let seconds = interval % 60
let minutes = (interval / 60)
return String(format: "%02d:%02d", minutes, seconds)
}
func startTimer() {
var duration=musictime.componentsSeparatedByString(":") //split 3 and 48
var count = duration[0].toInt()! * 60 + duration[1].toInt()! //224 second
timerCounter = NSTimeInterval( count )
NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: "onTimer:", userInfo: nil, repeats: true)
}
#objc func onTimer(timer:NSTimer!) {
// Here is the string containing the timer
// Update your label here
//println(stringFromTimeInterval(timerCounter))
statusLabel.text=stringFromTimeInterval(timerCounter)
timerCounter!--
}

Answer 1

You should take a look at NSDate property timeIntervalSinceNow. All you need is to set a future date as the endDate using NSDate method dateByAddingTimeInterval as follow:
class ViewController: UIViewController {
#IBOutlet weak var timerLabel: UILabel!
var remainingTime: NSTimeInterval = 0
var endDate: NSDate!
var timer = NSTimer()
override func viewDidLoad() {
super.viewDidLoad()
remainingTime = 228.0 // choose as many seconds as you want (total time)
endDate = NSDate().dateByAddingTimeInterval(remainingTime) // set your future end date by adding the time for your timer
timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: "updateLabel", userInfo: nil, repeats: true) // create a timer to update your label
}
func updateLabel() {
timerLabel.text = endDate.timeIntervalSinceNow.mmss
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
// you will need this extension to convert your time interval to a time string
extension NSTimeInterval {
var mmss: String {
return self < 0 ? "00:00" : String(format:"%02d:%02d", Int((self/60.0)%60), Int(self % 60))
}
var hmmss: String {
return String(format:"%d:%02d:%02d", Int(self/3600.0), Int(self / 60.0 % 60), Int(self % 60))
}
}

Answer 2

Well, by writing code. This is not a "Teach me how to program site. It's a site where you post questions about specific problems you are having with code you have written.
In short, though do the following:
Record your end time
let endInterval = NSDate.timeIntervalSinceReferenceDate() + secondsToEnd
Create a repeating timer that fires once/second.
Each time it fires, compute the number of seconds remaining to endInterval.
Calculate minutes remaining as
Int((endInterval-nowInterval)/60)
Calculate seconds remaining as
Int(endInterval-nowInterval)%60
There is also the new (to iOS 8) class NSDateComponentsFormatter, which I've read a little about but haven't used. I believe that will generate formatted timer intervals like hh:mm:ss for you automatically. You'd use the same approach I outlined above, but instead of calculating minutes and seconds yourself, use the NSDateComponentsFormatter.