Stopping Timer at Defined Amount of Time in Swift

Stopping timer at defined amount of time in Swift

Start by decoupling your expectations.

A "clock" is a container for the period of time from which it was started to now. Additionally, it could be "restarted", so it may need to know how long each previous run cycle was, this would then be added into the overall duration of the "clock"

The Timer is simply a way to run some code on periodical bases. Because a Timer only guarantees "at least" period, it should avoid been used for simple counter addition, as it can cause drift in your calculations (for a simple clock, it's probably not a big deal, but if you need any kind of precision, it's best to avoid it)

`SimpleClock`

import Foundation

public class SimpleClock {
    
    internal var startedAt: Date? = nil
    internal var totalRunningTime: TimeInterval = 0 // Used for pause/resume
    
    var isRunning: Bool = false {
        didSet {
            if isRunning {
                startedAt = Date()
            } else {
                totalRunningTime += currentCycleDuration
                self.startedAt = nil
            }
        }
    }
    
    // This is the amount of time that this cycle has been running,
    // that is, the amount of time since the clock was started to now.
    // It does not include other cycles
    internal var currentCycleDuration: TimeInterval {
        guard let startedAt = startedAt else {
            return 0
        }
        return Date().timeIntervalSince(startedAt)
    }
    
    func reset() {
        isRunning = false
        totalRunningTime = 0
    }
    
    // This is the "total" amount of time the clock has been allowed
    // to run for, excluding periods when the clock was paused
    var duration: TimeInterval {
        return totalRunningTime + currentCycleDuration
    }
    
}

Okay, this is pretty basic concept. It's just a container for recording when a "cycle" starts and stops and managing the "overall" duration (start/pause/resume cycles)

That's all fine and good, but what we really want is some way to determine if the period has "timeout" or not.

`AlarmClock`

import Foundation

class AlarmClock: SimpleClock {
    
    var timeout: TimeInterval = 0
    
    var hasExpired: Bool {
        return duration >= timeout
    }
    
    var timeRemaining: TimeInterval {
        return max(timeout - duration, 0)
    }
    
}

All this does is add a concept of a "timeout" period and provides some additional functionality that allows use to easily determine if the clock has expired and the amount of time remaining

Example

Okay, that's all nice a good, but how does this work (and help us)

Okay, this is a really simple example. It has a label and two buttons. One button starts/pauses the clock and the other resets it.

The label displays both the running time and the remaining time of the alarm clock. If he clock expires, it will automatically be reset.

The class contains a Timer which periodically "ticks" and allows the code to inspect that current state of the alarm clock.

Clocky

import UIKit

class ViewController: UIViewController {
    
    @IBOutlet weak var durationLabel: UILabel!
    @IBOutlet weak var cycleButton: UIButton!
    @IBOutlet weak var resetButton: UIButton!
    
    let alarmClock: AlarmClock = {
        let clock = AlarmClock()
        clock.timeout = 10.0
        return clock
    }()
    
    var timer: Timer? = nil
    
    var durationFormatter: DateComponentsFormatter {
        let formatter = DateComponentsFormatter()
        formatter.allowedUnits = [.minute, .second]
        formatter.unitsStyle = .abbreviated
        return formatter
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func cycleClock(_ sender: Any) {
        alarmClock.isRunning = !alarmClock.isRunning
        if alarmClock.isRunning {
            timer = Timer.scheduledTimer(timeInterval: 0.5, target: self, selector: #selector(tick), userInfo: nil, repeats: true)
        } else {
            timer?.invalidate()
            timer = nil
        }
        updateDurationLabel()
        updateCycleButtonState()
    }
    
    @IBAction func restartClock(_ sender: Any) {
        timer?.invalidate()
        timer = nil
        
        alarmClock.reset()
        updateDurationLabel()
        updateCycleButtonState()
    }
    
    func updateCycleButtonState() {
        if alarmClock.isRunning {
            cycleButton.setTitle("Pause", for: [])
        } else {
            cycleButton.setTitle("Start", for: [])
        }
    }
    
    func updateDurationLabel() {
        durationLabel.text = "\(durationFormatter.string(from: alarmClock.duration)!)/\(durationFormatter.string(from: alarmClock.timeRemaining)!)"
    }
    
    @objc func tick() {
        print("click")
        updateDurationLabel()
        if alarmClock.hasExpired {
            restartClock(self)
        }
    }
}

Now, you could also add some kind of "internal" thread to periodically check the state of the clock and call a delegate which could then bee used to update the UI, but the intention here is the decoupling of the concerns, and this means you're not adding yet another thread to the system unnecessarily (not saying you couldn't do, but it's just one more level of complexity I didn't want to add ;))

Swift question, how to stop my timer at 00:00 not negative number

Update your condition ... Currently when second goes below 0 .. then timer is invalidating ...

 if seconds < 10 && seconds >= 0 {
     secondsString = "0\(seconds)"

         if seconds == 0 {
            timer.invalidate()

            }
        }

Using Swift 3 Stopping a scheduledTimer, Timer continue firing even if timer is nil

Try to make the following changes to your code:

First, you have to change the way you declare timerTest

var timerTest : Timer?

then in startTimer before instantiating check if timerTest is nil

func startTimer () {
  guard timerTest == nil else { return }

  timerTest =  Timer.scheduledTimer(
      timeInterval: TimeInterval(0.3),
      target      : self,
      selector    : #selector(ViewController.timerActionTest),
      userInfo    : nil,
      repeats     : true)
}

Finally in your stopTimerTest you invalidate timerTest if it isn't nil

func stopTimerTest() {
  timerTest?.invalidate()
  timerTest = nil
}

How to stop timer in Text view?

Here is a demo of possible approach - as .timer run from now for ever (by design), the idea is to replace it with regular text once specified period is over.

Tested with Xcode 12b3 / iOS 14.

demo

struct DemoView: View {
    @State private var run = false

    var body: some View {
        VStack {
            if run {
                Text(nextRollTime(in: 10), style: .timer)
            } else {
                Text("0:00")
            }
        }
        .font(Font.system(.title, design: .monospaced))
        .onAppear {
            self.run = true
        }
    }

    func nextRollTime(in seconds: Int) -> Date {
        let date = Calendar.current.date(byAdding: .second, value: seconds, to: Date())
        DispatchQueue.main.asyncAfter(deadline: .now() + Double(seconds)) {
            self.run = false
        }
        return date ?? Date()
    }
}

Swift - Timer doesn't stop

After research I found a solution,

The only thing that worked for me is to create functions in AppDelegate file and call them when needed,

Here is the code, the timerSwitch function:

    func timerSwitch()
    {
        if (timerStatus) {
            checkStateTimer = Timer.scheduledTimer(
                timeInterval: 60, 
                target:self, 
                selector: #selector(self.yourFunction), 
                userInfo: nil, repeats: true)
        } else {
            checkStateTimer?.invalidate()
        }
    }

    func stopTimer()
    {
        timerStatus = false
        timerSwitch()

    }

    func startTimer()
    {
        timerStatus = true
        timerSwitch()

    }

While 'yourFunction' is what you want to execute when the timer starts,

In my case is sending heartbeat.

Then I called the timerSwitch is the following functions in AppDelegate:

    func applicationWillResignActive(_ application: UIApplication) {
        stopTimer()
    }

    func applicationDidEnterBackground(_ application: UIApplication) {
        stopTimer() 
    }

    func applicationDidBecomeActive(_ application: UIApplication) {
        startTimer()
    }

swift: stop countdown timer at zero

Remember, your timer doesn't count down to zero - you implement that in your code. The timer just fires every second.

In your updateTime function, you need to invalidate the timer, and call your sound function, when the timer runs out

How to capture the elapsed time when a timer is paused

Get the time when the user pauses the app as a new date(), and also the time when the user resumes the app. Get the difference between those two dates/times and subtract that from the total time to get the correct total time for the practice session.

For example, you could have a variable that keeps track of total pause time:

var totalPauseTime: TimeInterval = 0
var pauseStartTime: Date?

It gets recalculated every time a user taps the pause button to resume (after previously having tapped it to pause):

@IBAction func pauseButtonTapped(_ sender: DesignableButton)
    {
        if resumeTapped == false
        {
            pauseStartTime = Date() 
            timer.invalidate()
            resumeTapped = true
            sender.setImage(UIImage(named: "Resume"), for: .normal)

        } else {
            if let pauseStartTime = pauseStartTime {
                totalPauseTime += Date().timeIntervalSinceReferenceDate - pauseStartTime.timeIntervalSinceReferenceDate
            }
            runTimer()

            resumeTapped = false
            sender.setImage(UIImage(named: "Pause"), for: .normal)
        }
    }

Haven't actually tested the above code but it should give an idea. Then you subtract totalPauseTime at the point in your code where you calculate the total session time.

Swift | The timer wont stop on invalidate call, rather speeds up?

As far as I can recognize, you have 2 mistakes.

First one is mentioned by the other answer. It is a true suggestion that you shouldn't always add a new UIButton and should use just hide/unhide property for each button.

Second mistake is on how you add a target. You are using .allTouchEvents, however you might intent to use .touchUpInside as your control state.

Kindly see the below corrected code for your reference:

import UIKit

class ViewController: UIViewController {

@IBOutlet weak var titleLabel: UILabel!

var startButton: UIButton!
var stopButton: UIButton!
var timer: Timer!
var counter: Double = 0.0

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    startButton = UIButton(frame: CGRect(x: 0, y: UIScreen.main.bounds.height * 0.9 , width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height * 0.1))
    startButton.setTitle("Start Timer", for: .normal)
    startButton.setTitleColor(.white , for: .normal)
    startButton.backgroundColor = .red
    startButton.addTarget(self, action: #selector(playButton(_:)), for: .touchUpInside)
    self.view.addSubview(startButton)
    self.startButton.isHidden = false

    stopButton = UIButton(frame: CGRect(x: 0, y: UIScreen.main.bounds.height * 0.9 , width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height * 0.1))
    stopButton.setTitle("Stop Timer", for: .normal)
    stopButton.setTitleColor(.white , for: .normal)
    stopButton.backgroundColor = .red
    stopButton.addTarget(self, action: #selector(pauseButton(_:)), for: .touchUpInside)
    self.view.addSubview(stopButton)
    self.stopButton.isHidden = true
}

@objc func playButton(_ sender : Any) {
    timer = Timer.scheduledTimer(timeInterval: 1, target: self , selector: #selector(updateTimer), userInfo: nil, repeats: true)

    startButton.isEnabled = false
    stopButton.isEnabled = true
    startButton.isHidden = true
    stopButton.isHidden = false
}

@objc func pauseButton(_ sender: Any) {
    timer.invalidate()

    stopButton.isHidden = true
    startButton.isHidden = false
    startButton.isEnabled = true
    stopButton.isEnabled = false
}

@objc func updateTimer(_ sender : Any)
{
    counter += 0.1
    titleLabel.text = String(format: "%.1f", counter)
}
}

Stopping AVAudioPlayer at a certain time in Swift

You could use a Timer to check the currentTime property of your AVAudioPlayer object.

For Example

Start the timer when you start playing the audio. Adjusting the check interval 0.1 based on the level of accuracy required.

var timer:Timer!

timer = Timer.scheduledTimerWithTimeInterval(
    0.1, 
    target: self, 
    selector: "checkTime",
    userInfo: nil, 
    repeats: true
)

Then create the function that the timer runs every 0.1 second to check the audio players current time against your own value where END_TIME could be updated or replaced by your songEnd logic.

let END_TIME = 10.0

func checkTime() {
    if self.audioPlayer.currentTime >= END_TIME {
        self.audioPlayer.stop()
        timer.invalidate()
    }
}

Stopping Timer at Defined Amount of Time in Swift