I want my countdown timer to suspend and then resume when the app leaves / returns to focus, using the time away to calculate how much time should be deducted.
I am using the app delegate file (not sure thats the right location? or if they are meant to be in the view controllers file as functions of their own?)
Issue is im getting a lot of errors such as:
Value of type 'AppDelegate' has no member 'restTimer'
Use of unresolved identifier 'nextFireDate'
Use of unresolved identifier 'selector'
restTimer was declared as a timer in my view controllers file but when i tried these blocks in that file i got an equal number of errors for unresolved identifiers
and using the following 2 code blocks
func applicationWillResignActive(_ application: UIApplication) {
guard let t = self.restTimer else { return }
nextFireDate = t.fireDate
t.invalidate()
and
func applicationDidBecomeActive(_ application: UIApplication) {
guard let n = nextFireDate else { return }
let howMuchLonger = n.timeIntervalSinceDate(NSDate())
if howMuchLonger < 0 {
print("Should have already fired \(howMuchLonger) seconds ago")
target!.performSelector(selector!)
} else {
print("should fire in \(howMuchLonger) seconds")
Timer.scheduledTimerWithTimeInterval(howMuchLonger, target: target!, selector: selector!, userInfo: nil, repeats: false)
}
}
UPDATE: Added full views code due to issue incorporating the answer
import Foundation
import UIKit
class RestController: UIViewController {
@IBOutlet weak var restRemainingCountdownLabel: UILabel!
@IBOutlet weak var setsRemainingCountdownLabel: UILabel!
@IBOutlet weak var numberOfSetsLabel: UILabel!
@IBOutlet weak var numberOfRestLabel: UILabel!
@IBOutlet weak var adjustSetsStepper: UIStepper!
@IBOutlet weak var adjustRestStepper: UIStepper!
var startDate: Date!
let startDateKey = "start.date"
let interval = TimeInterval(20)
var restTimer: Timer!
var restCount = 0
var setCount = 0
var selectedTime = 1
var selectedSets = 1
private let resignDateKey = "resign.date"
@IBAction func endSetPressed(_ sender: Any) {
if (setCount > 0){
setCount -= 1
setsRemainingCountdownLabel.text = String(setCount)
}
handleTimer()
}
@IBAction func setStepperValueChanged(_ sender: UIStepper) {
numberOfSetsLabel.text = Int(sender.value).description
self.setCount = Int(sender.value)
self.selectedSets = setCount
setsRemainingCountdownLabel.text = String(setCount)
}
@IBAction func restStepperValueChanged(_ sender: UIStepper) {
numberOfRestLabel.text = Int(sender.value).description
let timeMinSec = timeFormatted(totalSeconds: Int(sender.value)*60)
restRemainingCountdownLabel.text = timeMinSec
self.selectedTime = Int(sender.value)
restCount = self.selectedTime * 60
}
@IBAction func resetSetsButton(_ sender: Any) {
setCount = Int(adjustSetsStepper.value)
setsRemainingCountdownLabel.text = String(setCount)
}
override func viewDidLoad() {
super.viewDidLoad()
numberOfSetsLabel.text = String(selectedSets)
numberOfRestLabel.text = String(selectedTime)
createTimer(interval: interval)
NotificationCenter.default.addObserver(self, selector: #selector(willResignActive), name: NSNotification.Name.UIApplicationWillResignActive, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(didBecomeActive), name: NSNotification.Name.UIApplicationDidBecomeActive, object: nil)
}
deinit {
NotificationCenter.default.removeObserver(self)
}
@objc private func willResignActive(notification: Notification) {
print("resigning")
guard restTimer.isValid else {
UserDefaults.standard.removeObject(forKey: startDateKey)
return
}
restTimer.invalidate()
UserDefaults.standard.set(Date(), forKey: startDateKey)
}
@objc private func didBecomeActive(notification: Notification) {
print("resume")
if let startDate = UserDefaults.standard.object(forKey: startDateKey) as? Date {
let elapsed = -startDate.timeIntervalSinceNow
print("elpased time: \(elapsed) remaining time: \(interval - elapsed)")
if elapsed > interval {
timerUp()
} else {
createTimer(interval: interval - elapsed)
}
}
}
private func createTimer (interval: TimeInterval) {
restTimer = Timer.scheduledTimer(withTimeInterval: interval , repeats: false) {[weak self] _ in
self?.timerUp()
}
startDate = Date()
}
private func timerUp() {
print("At least \(interval) seconds has elapsed")
}
func handleSets() {
if (setCount > 0) {
self.restCount = self.selectedTime * 60
}
handleTimer()
}
func handleTimer() {
if (restTimer?.isValid ?? false) {
restTimer?.invalidate()
restTimer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(RestController.updateTimer), userInfo: nil, repeats: true)
} else {
restTimer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(RestController.updateTimer), userInfo: nil, repeats: true)
}
}
func updateTimer() {
if (restCount > 0){
restCount -= 1
} else if (restCount == 0){
restTimer?.invalidate()
}
restRemainingCountdownLabel.text = timeFormatted(totalSeconds: restCount)
}
func timeFormatted(totalSeconds: Int) -> String {
let seconds: Int = totalSeconds % 60
let minutes: Int = (totalSeconds / 60) % 60
return String(format: "%02d:%02d", minutes, seconds)
}
