How to capture the elapsed time when a timer is paused - ios

Question

I have put together a count down timer so the user can recored their practice seasons. I have it working fine except for one part. The user is allowed to pause the session. The problem with the code thus far, is that the timer code pauses but the time keeps running.
For example, if the user sets the timer for 5 minutes and taps the start button, then midway through the user taps pauses and waits 2 minutes (which means the elapsed time is now 7 minutes) the practice time presented when the timer ends is 7 minutes instead fo 5 minutes. If the user cancels the session it's fine but only because I'm setting a hard start and end time.
My question is how do I capture the practice time if the user pauses the timer?
Here's an explanation of the UI:
The timerLabel contains the running time
The minutesLabel shows the number of minutes the user set the timer to
The hoursLabel shows the number of hours the user set the timer to
There are two sliders. One for setting the minutes and one fo setting the hours
There are also two buttons. A Play/Cancel button and a Pause/Resume button
Thanks in advance!
import UIKit
import AVFoundation
class Practice_Timmer_VC: UIViewController
{
#IBOutlet weak var navBar: UINavigationItem!
#IBOutlet weak var viewLabel: DesignableLabel!
#IBOutlet weak var timerLabel: DesignableLabel!
#IBOutlet weak var theTabbar: UITabBar!
#IBOutlet weak var minutesLabel: UILabel!
#IBOutlet weak var hoursLabel: UILabel!
var seconds: Int = 60
var timer = Timer()
var isTimerRunning: Bool = false
var resumeTapped: Bool = false
var theTime: String = ""
var startTime: Date = Date()
var endTime: Date = Date()
var total: Int = 0
var chimeSoundEffect: AVAudioPlayer?
override func viewDidLoad()
{
super.viewDidLoad()
theTabbar.selectedItem = theTabbar.items![4]
view.backgroundColor = UIColor(patternImage: UIImage(named: "Carbon.png")!)
startButton.isEnabled = true
pauseButton.isEnabled = false
populateTheTimer()
}// End of viewDidLoad
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
startButton.setImage(UIImage(named: "Play"), for: .normal)
}
func populateTheTimer()
{
let theName = ModelData.getTheTrickName()
navBar.title = theName
}
func getTheDifference(start: Date, end: Date)
{
let theFormatter = DateComponentsFormatter()
theFormatter.allowedUnits = [.hour, .minute]
theFormatter.unitsStyle = .full
theTime = theFormatter.string(from: start, to: end) ?? ""
}
func formattedDate() -> String
{
let formatter = DateFormatter()
let date = Date()
formatter.locale = Locale.current
formatter.dateStyle = .medium
return formatter.string(from: date)
}
func timeString(time: TimeInterval) -> String
{
let hours = Int(time) / 3600
let minutes = Int(time) / 60 % 60
let seconds = Int(time) % 60
return String(format:"%02i:%02i:%02i", hours, minutes, seconds)
}
func runTimer()
{
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: (#selector(self.updateTimer)), userInfo: nil, repeats: true)
isTimerRunning = true
pauseButton.isEnabled = true
}
#objc func updateTimer()
{
if seconds < 1
{
timer.invalidate()
endTime = Date()
getTheDifference(start: startTime, end: endTime)
startButton.setImage(UIImage(named: "Play"), for: .normal)
startButton.isEnabled = true
pauseButton.isEnabled = false
playTheSound()
showAlert()
} else {
seconds -= 1
timerLabel.text = timeString(time: TimeInterval(seconds))
}
}
func showAlert()
{
let theAlert = UIAlertController(title: "Practice Ended", message: "\(formattedDate())\nPracticed for: \(theTime)", preferredStyle: .alert)
let saveTheInfo = UIAlertAction(title: "Save Practice", style: .default) { (saveAction) in
self.gotoAddEdit()
}
let cancel = UIAlertAction(title: "Cancel", style: .cancel) { (cancelAction) in
}
theAlert.addAction(saveTheInfo)
theAlert.addAction(cancel)
present(theAlert, animated: true)
}
func playTheSound()
{
let path = Bundle.main.path(forResource: "chime.mp3", ofType: nil)!
let theURL = URL(fileURLWithPath: path)
do {
chimeSoundEffect = try AVAudioPlayer(contentsOf: theURL)
chimeSoundEffect?.play()
} catch {
}
}
func gotoAddEdit()
{
let sb = UIStoryboard(name: "Main", bundle: nil)
if let addEdit = sb.instantiateViewController(withIdentifier: "Practice_Log_VC") as? Practice_Log_VC
{
addEdit.passData = "\(formattedDate())\nPracticed for: \(theTime)"
addEdit.delegate = self as? Timer2PracticeLog_Delegate
self.navigationController?.pushViewController(addEdit, animated: ModelData.isAnimation())
self.navigationController?.view.semanticContentAttribute = .forceLeftToRight
}
}
#IBOutlet weak var startButton: DesignableButton!
#IBAction func startButtonTapped(_ sender: DesignableButton)
{
let minutes2Seconds = Int(minutesSliderOutlet.value) * 60
let hours2Seconds = Int(hoursSliderOutlet.value) * 3600
seconds = Int(minutes2Seconds + hours2Seconds)
if isTimerRunning == false // Start
{
if seconds > 0
{
startTime = Date()
sender.setImage(UIImage(named: "Cancel_Video"), for: .normal)
runTimer()
} else {
view.sendConfirmationAlert(theTitle: "Error! Practice time is set to 0.", theMessage: "Please set the practice time.", buttonTitle: "OK")
minutesSliderOutlet.value = 1
minutesLabel.text = "1 Minute"
}
} else { // Cancel
endTime = Date()
timer.invalidate()
seconds = 0
getTheDifference(start: startTime, end: endTime)
sender.setImage(UIImage(named: "Play"), for: .normal)
minutesSliderOutlet.value = 1
minutesLabel.text = "1 Minute"
hoursSliderOutlet.value = 0
hoursLabel.text = "0 Hours"
timerLabel.text = timeString(time: TimeInterval(seconds))
isTimerRunning = false
pauseButton.isEnabled = false
showAlert()
}
}
#IBOutlet weak var pauseButton: DesignableButton!
#IBAction func pauseButtonTapped(_ sender: DesignableButton)
{
if resumeTapped == false
{
timer.invalidate()
resumeTapped = true
sender.setImage(UIImage(named: "Resume"), for: .normal)
} else {
runTimer()
resumeTapped = false
sender.setImage(UIImage(named: "Pause"), for: .normal)
}
}
#IBOutlet weak var minutesSliderOutlet: UISlider!
#IBAction func minuteSlider(_ sender: UISlider)
{
let minutes = Int(sender.value)
if minutes > 1
{
minutesLabel.text = String(minutes) + " Minutes"
} else {
minutesLabel.text = String(minutes) + " Minute"
}
}
#IBOutlet weak var hoursSliderOutlet: UISlider!
#IBAction func hoursSlider(_ sender: UISlider)
{
let hours = Int(sender.value)
if hours > 1
{
hoursLabel.text = String(hours) + " Hours"
} else {
hoursLabel.text = String(hours) + " Hour"
}
}
}// End of Class

Answer 1

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.