Code not running when returning from background. If I suspend the app, close it out completely and re-open it calculates the time perfectly.
How can I get it to run when user leaves the app and returns.
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
if let lastTimerStartTime = UserDefaults.standard.value(forKey: "lastTimerStartTime") as? Date,
let totalTime = UserDefaults.standard.value(forKey: "totalTime") as? Double {
let timeSinceStartTime = Date() - lastTimerStartTime
if timeSinceStartTime < totalTime {
seconds = totalTime - timeSinceStartTime
runTimer()
} else {
timeLabel.text = timeString(time: TimeInterval(seconds))
}
} else {
timeLabel.text = timeString(time: TimeInterval(seconds))
}
}
#IBAction func startBtn(_ sender: Any) {
runTimer()
}
func runTimer() {
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: (#selector(ViewController.updateTimer)), userInfo: nil, repeats: true)
UserDefaults.standard.set(Date(), forKey: "lastTimerStartTime")
UserDefaults.standard.set(seconds, forKey: "totalTime")
}
#objc func updateTimer(){
seconds -= 1
timeLabel.text = timeString(time: TimeInterval(seconds))
}
You need to add code to listen for suspend and resume events. (UIApplication.willResignActiveNotification and UIApplication. didBecomeActiveNotification).
When you get notified that you are going to resign being the active app, you’ll need to save the amount time remaining (or time elapsed) whatever makes sense.
You don’t know if your app will be resumed or killed, so you will need to save the info to UserDefaults, and then pick it up either when handing a didBecomeActiveNotification or when your app gets launched again.
If your app is moved the background and then brought back to the front without being terminated, your viewDidAppear method won’t get called because your view controller’s view never left the screen.
I am creating a trivia app in swift and I have a timer that counts down each question. However as the user progresses with each question the timer speeds up. Can someone help me fix this?
My runGameTimer function:
func runGameTimer()
{
gameTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(RockTriviaViewController.updateGameTimer), userInfo: nil, repeats: true)
}
My updateGameTimer function:
#objc func updateGameTimer()
{
gameInt -= 1
timerLabel.text = String(gameInt)
if (gameInt == 0)
{
gameTimer.invalidate()
/*
if (currentQuestion != rockQuestions[questionSet].count)
{
newQuestion()
}
else
{
performSegue(withIdentifier: "showRockScore", sender: self)
}
*/
}
}
Where I call my code:
func newQuestion()
{
gameInt = 11
runGameTimer()
rockQuestion.text = rockQuestions[questionSet][currentQuestion]
rightAnswerPlacement = arc4random_uniform(3)+1
var Button: UIButton = UIButton()
var x = 1
for i in 1...3
{
Button = view.viewWithTag(i) as! UIButton
if(i == Int(rightAnswerPlacement))
{
Button.setTitle(rockAnswers[questionSet][currentQuestion][0], for: .normal)
}
else
{
Button.setTitle(rockAnswers[questionSet][currentQuestion][x], for: .normal)
x = 2
}
}
currentQuestion += 1
}
You're calling runGameTimer() in every call to newQuestion(). If a timer was already running then you'll add a new timer each time, and they will all call your selector. So if you have 3 timers running, your selector will be called 3x as often. That's not what you want.
Change your timer variable to be weak:
weak var gameTimer: Timer?
And then in runGameTimer invalidate the timer before creating a new one, using optional chaining:
func runGameTimer() {
gameTimer?.invalidate() //This will do nothing if gameTimer is nil.
//it will also cause the gameTimer to be nil since it's weak.
gameTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(RockTriviaViewController.updateGameTimer), userInfo: nil, repeats: true)
}
By making the game timer weak it will get set to nil as soon as it's invalidated. (When you schedule a timer the system retains it while it is running so it stays valid as long as it continues to run.)
By using optional chaining to reference the timer:
gameTimer?.invalidate()
The code doesn't do anything if gameTimer is nil.
I want the timer to run even when I close the application. I want it to work in the background counter. the timer goes back one second when I run it.(counter) How can I do that?
class TimerViewController: UIViewController {
var selectedDay: String?
var seconds =
var timer = Timer()
#IBAction func start(_ sender: AnyObject) {
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(TimerViewController.counter), userInfo: nil, repeats: true)
sliderOutlet.isHidden = true
startOutlet.isHidden = true
}
#objc func counter() {
seconds -= 1
favoriteDayTextField.text = String(seconds) + " Seconds"
var bgTask = UIBackgroundTaskIdentifier(rawValue: seconds)
bgTask = UIApplication.shared.beginBackgroundTask(expirationHandler: {
UIApplication.shared.endBackgroundTask(bgTask)
})
if (seconds == 0) {
timer.invalidate()
if self.button.isOn {
updateState()
} else {
updateState1()
}
}
}
}
I am not clear what you want to achieve. Suppose you want to update the label after the timer has started each 1 second. Then one approach will be:-
Start the timer in view did load if the duration is remaining.
Register for applicationWillTerminate
In application will terminate save the passed duration and terminated time to calculate remaining time in next launch.
var remainingDuration: TimeInterval!
override func viewDidLoad() {
super.viewDidLoad()
let remainingDurationFromLastLaunch = UserDefaults.standard.object(forKey: "duration") as? TimeInterval ?? 0
let lastTerminatedTime = UserDefaults.standard.object(forKey: "lastTerminatedDate") as? Date ?? Date()
if Date().timeInterval(since: lastTerminatedTime) > remainingDurationFromLastLaunch {
remainingDuration = remainingDurationFromLastLaunch - Date().timeInterval(since: lastTerminatedTime)
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(TimerViewController.counter), userInfo: nil, repeats: true)
NotificationCenter.default.addObserver(self, selector: #selector(TimerViewController.applicationWillTerminate), name: NSNotification.Name.UIApplicationWillTerminate, object: nil)
} else { //Duration is passed....Do whatever you want
}
}
#objc func counter() {
remainingDuration -= 1
if remainingDuration == 0 { //Duration is passed....Do whatever you want
timer.invalidate()
timer = nil
} else {
favoriteDayTextField.text = String(remainingDuration) + " Seconds"
}
}
#objc func applicationWillTerminate() {
if timer != nil {
backgroundTask = UIApplication.shared.beginBackgroundTask { [weak self] in
UserDefaults.standard.set(remainingDuration, forKey: "duration")
UserDefaults.standard.set(Date(), forKey: "lastTerminatedDate")
}
self?.endBackgroundTask()
}
}
func endBackgroundTask() {
UIApplication.shared.endBackgroundTask(backgroundTask)
backgroundTask = UIBackgroundTaskInvalid
}
The only way for your iOS application to perform some action even while it is in the background is to use Background Modes .
However you cannot perform anything and everything while your
application is in background
There are certain limitations to the type of tasks that you can perform . I have attached a really good article for your reference
Background Modes Tutorial
However, I am not sure if you can initiate and continue a timer sort of functionality while your application is in background
Though, keep in mind , once your application is closed (i.e. by double tapping the home button and swiping the application window up to close it completely) , not even Background modes work at that point because the user does not want to run your app anymore, even in the background
I am a school teacher and we have been 'ordered' to use a specific timer for our lessons, which low and behold doesn't work on our apple iMac's. I am trying to create my own in xcode and so far have created a basic window which will countdown a label in seconds. I have at the moment assigned the buttons and they work (in increments of 60 seconds).
This works and is fine but ideally i would like the label to display minutes and seconds instead (much easier for the kids). What is the best way to code this? Last time i used xcode was in 2009 and i am way out of date now!! Thanks in advance
--
#objc func updateTimer() {
seconds -= 1 //This will decrement(count down)the seconds.
countdownLabel.stringValue = "\(seconds)" //This will update the label.
}
--
#objc func runTimer() {
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector:(#selector(ViewController.updateTimer)), userInfo: nil, repeats: true)
}
--
#IBAction func threeMin(_ sender: Any) {
seconds = 180
runTimer()
}
--
There are many solutions. A convenient one is DateComponentsFormatter
let formatter : DateComponentsFormatter = {
let formatter = DateComponentsFormatter()
formatter.allowedUnits = [.minute, .second]
return formatter
}()
#objc func updateTimer() {
seconds -= 1
countdownLabel.stringValue = formatter.string(from: TimeInterval(seconds))!
}
Some improvements:
Assign tags to all buttons with their value in seconds for example set the tag of the threeMin button to 180. Then use only one IBAction and connect all buttons to that action.
In the action first check if the timer is running and start it only if it's not running
var timer : Timer?
#IBAction func startTimer(_ sender: NSButton) {
if timer == nil {
seconds = sender.tag
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(ViewController.updateTimer), userInfo: nil, repeats: true)
}
}
Create a function to stop the timer reliably
func stopTimer() {
if timer != nil {
timer?.invalidate()
timer = nil
}
}
In the updateTimer() function stop the timer if seconds is 0
#objc func updateTimer() {
seconds -= 1
countdownLabel.stringValue = formatter.string(from: TimeInterval(seconds))!
if seconds == 0 { stopTimer() }
}
I'm developing a game and I want to create a pause menu. Here is my code:
self.view?.paused = true
but NSTimer.scheduledTimerWithTimeInterval still running...
for var i=0; i < rocketCount; i++ {
var a: NSTimeInterval = 1
ii += a
delaysShow = 2.0 + ((stimulus + interStimulus) * ii)
var time3 = NSTimer.scheduledTimerWithTimeInterval(delaysShow!, target: self, selector: Selector("showRocket:"), userInfo: rocketid[i], repeats: false)
}
I want time3 to pause the timer when player click pause menu and continue run the timer when player come back to the game, but how can I pause NSTimer.scheduledTimerWithTimeInterval? help me please.
You need to invalidate it and recreate it. You can then use an isPaused bool to keep track of the state if you have the same button to pause and resume the timer:
var isPaused = true
var timer = NSTimer()
#IBAction func pauseResume(sender: AnyObject) {
if isPaused{
timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: Selector("somAction"), userInfo: nil, repeats: true)
isPaused = false
} else {
timer.invalidate()
isPaused = true
}
}
To Start:
timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("updateView"), userInfo: nil, repeats: true)
To Resume:
timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("updateView"), userInfo: nil, repeats: true)
To Pause:
timer.invalidate
This worked for me. The trick is that do not look for something like "timer.resume" or "timer.validate". Just use "the same code for starting a timer" to resume it after the pause.
To start
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(ViewController.action), userInfo: nil, repeats: true)
To pause
timer.invalidate()
To reset
time += 1
label.text = String(time)
'label' is the timer on output.
I was just working through a similar problem with my game, and found an easy solution.
First I should point out like others have, that Timer and NSTimer doesn't have a pause function. You have to stop the Timer with Timer.invalidate(). After invalidating a Timer, you must initialize it again to start the Timer. To quote from https://developer.apple.com/documentation/foundation/timer, the function .invalidate() -
Stops the timer from ever firing again and requests its removal from
its run loop.
To pause a timer we can use Timer.fireDate, this is where Timer (and NSTimer) saves the date for when the Timer will fire in the future.
Here's how we can pause a Timer by saving the seconds left that the Timer has until it fires again.
//The variable we will store the remaining timers time in
var timeUntilFire = TimeInterval()
//The timer to pause
var gameTimer = Timer.scheduledTimer(timeInterval: delaysShow!, target: self, selector: #selector(GameClass.showRocket), userInfo: rocketid[i], repeats: false)
func pauseTimer()
{
//Get the difference in seconds between now and the future fire date
timeUntilFire = gameTimer.fireDate.timeIntervalSinceNow
//Stop the timer
gameTimer.invalidate()
}
func resumeTimer()
{
//Start the timer again with the previously invalidated timers time left with timeUntilFire
gameTimer = Timer.scheduledTimer(timeInterval: timeUntilFire, target: self, selector: #selector(GameClass.showRocket), userInfo: rocketid[i], repeats: false)
}
Note: Don't invalidate() the Timer before getting the fireDate. After invalidate() is called the Timer seems to reset the fireDate to 2001-01-01 00:00:00 +0000.
2nd Note: A timer can potentially fire after its set fireDate. This will lead to a negative number, which will default the Timer to run after 0.1 milliseconds instead. https://developer.apple.com/documentation/foundation/timer/1412416-scheduledtimer
To stop it
time3.invalidate()
To start it again
time3.fire()
You can not resume the timer back.
Instead of resuming - just create a new timer.
class SomeClass : NSObject { // class must be NSObject, if there is no "NSObject" you'll get the error at runtime
var timer = NSTimer()
init() {
super.init()
startOrResumeTimer()
}
func timerAction() {
NSLog("timer action")
}
func pauseTimer() {
timer.invalidate
}
func startOrResumeTimer() {
timer = NSTimer.scheduledTimerWithTimeInterval(0.5, target: self, selector: Selector("timerAction"), userInfo: nil, repeats: true)
}
}
Even though the solutions exposed here are good, I thought an important insight was missing. Like a lot of people here explained, timer invalidate() and recreate is the best option. But one could argue that you could do something like this:
var paused:Bool
func timerAction() {
if !paused {
// Do stuff here
}
}
is easier to implement, but it will be less efficient.
For energy impact reasons, Apple promotes avoiding timers whenever possible and to prefer event notifications. If you really need to use a timer, you should implement pauses efficiently by invalidating the current timer. Read recommendations about Timer in the Apple Energy Efficiency Guide here:
https://developer.apple.com/library/content/documentation/Performance/Conceptual/EnergyGuide-iOS/MinimizeTimerUse.html
SWIFT3
Global Declaration :
var swiftTimer = Timer()
var count = 30
var timer = Timer()
#IBOutlet weak var CountDownTimer: UILabel!
viewDidLoad
override func viewDidLoad() {
super.viewDidLoad()
BtnStart.tag = 0
}
Triggered IBACTION :
#IBAction func BtnStartTapped(_ sender: Any) {
if BtnStart.tag == 0 {
BtnStart.setTitle("STOP", for: .normal)
timer = Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(ScoreBoardVC.update), userInfo: nil, repeats: true)
BtnStart.tag = 1
} else {
BtnStart.setTitle("START", for: .normal)
timer.invalidate()
BtnStart.tag = 0
}
}
Function that Handles The things :
func update(){
if(count > 0){
let minutes = String(count / 60)
let ConvMin = Float(minutes)
let minuttes1 = String(format: "%.0f", ConvMin!)
print(minutes)
let seconds = String(count % 60)
let ConvSec = Float(seconds)
let seconds1 = String(format: "%.0f", ConvSec!)
CountDownTimer.text = (minuttes1 + ":" + seconds1)
count += 1
}
}
Pause timer : timer.invalidate()
and
Resume timer : recreate timer. it's work fine.
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(mainController.updateTimer), userInfo: nil, repeats: true)