I have been trying to refill in game lives with a timer, but whenever I leave a view and return, the timer duplicates and becomes faster. I have tried to address this with the Timer?.isValid function to only run the timer when it is invalid so it never duplicates, but it cannot seem to check is the timer is invalid in an if statement.
This is the if statement that I have been using so far:
if (myTimer?.isValid){
} else{
//start timer
}
Any help would be appreciated, thanks.
I recommend to use self-checking startTimer() and stopTimer() functions, the timer will be started only if it's not currently running, the stop function sets the timer variable reliably to nil.
var timer : Timer?
func startTimer()
{
if timer == nil {
timer = Timer.scheduledTimer...
}
}
func stopTimer()
{
if timer != nil {
timer!.invalidate()
timer = nil
}
}
You need to check if your Timer instance isValid (not the Timer class), let's say: if myTimer.isValid? {}.
Related
I am trying to cancel a delayed execution of a function running on the main queue, in a tap gesture, I found a way to create a cancellable DispatchWorkItem, but the issue I have is that it's getting created every time while tapping, and then when I cancel the execution, I actually cancel the new delayed execution and not the first one.
Here is a simpler example with a Timer instead of a DispatchQueue.main.asyncAfter:
.onTapGesture {
isDeleting.toggle()
let timer = Timer.scheduledTimer(withTimeInterval: 2.0, repeats: false) { timer in
completeTask()
}
if !isDeleting {
timer.invalidate()
}
}
completeTask:
private func completeTask() {
tasksViewModel.deleteTask(task: task) // task is declared above this func at the top level of the struct and so is tasksViewModel, etc.
guard let userID = userViewModel.id?.uuidString else { return }
Task {
//do some async stuff
}
}
As you can see if I click it once the timer fires, but if I click it again, another timer fires and straight away invalidates, but the first timer is still running.
So I have to find a way to create only one instance of that timer.
I tried putting it in the top level of the struct and not inside the var body but the issue now is that I can't use completeTask() because it uses variables that are declared at the same scope.
Also, can't use a lazy initialization because it is an immutable struct.
My goal is to eventually let the user cancel a timed task and reactivate it at will on tapping a button/view. Also, the timed task should use variables that are declared at the top level of the struct.
First of all you need to create a strong reference of timer on local context like so:
var timer: Timer?
and then, set the timer value on onTapGesture closure:
.onTapGesture {
isDeleting.toggle()
self.timer = Timer.scheduledTimer(withTimeInterval: 2.0, repeats: false) { timer in
completeTask()
}
if !isDeleting {
timer.invalidate()
}
}
and after that you can invalidate this Timer whenever you need by accessing the local variable timer like this:
func doSomething() {
timer?.invalidate()
}
that is my solution mb can help you
var timer: Timer?
private func produceWorkItem(withDelay: Double = 3) {
scrollItem?.cancel()
timer?.invalidate()
scrollItem = DispatchWorkItem.init { [weak self] in
self?.timer = Timer.scheduledTimer(withTimeInterval: withDelay, repeats: false) { [weak self] _ in
self?.goToNextPage(animated: true, completion: { [weak self] _ in self?.produceWorkItem() })
guard let currentVC = self?.viewControllers?.first,
let index = self?.pages.firstIndex(of: currentVC) else {
return
}
self?.pageControl.currentPage = index
}
}
scrollItem?.perform()
}
for stop use scrollItem?.cancel()
for start call func
I have a function like below:
func startTimer() {
let appDelegate = UIApplication.shared.delegate as! AppDelegate
DispatchQueue.main.async {
appDelegate.TIMER = Timer.scheduledTimer(withTimeInterval: self.REPEAT_TIME, repeats: true, block: { timer in
self.sendData(programID: self.MAIN_THREAD)
do {
try ...
}
catch let error {
...
}
})
}
}
Timer Stop Function:
func stopTimer() {
let appDelegate = UIApplication.shared.delegate as! AppDelegate
if (appDelegate.TIMER != nil) {
appDelegate.TIMER?.invalidate()
appDelegate.TIMER = nil
}
}
I want to know that
is there any chance to start multiple timer instances if I call this function without stopping?
And how about this case,(does this stopped only one timer & continue running another timer?)
Start the timer → Start again → Stop
is there any chance to start multiple timer instances if I call this function without stopping?
Yes, startTimer will start another timer w/o stopping previous one, but as you store it in property TIMER you will loose reference to previously scheduled timer, so will be not able to stop it until end.
And how about this case,(does this stopped only one timer & continue running another timer?)
Start the timer → Start again → Stop
Yes, it will stop last started timer and all other previously started timers will continue for self.REPEAT_TIME.
Okay I'm trying to do something similar to iTunes not sure if it's still the same. It's when you click a song and it gives a sample of the audio file. This is my code looks.
The music file is like 2-3min long. I got the start time to start at 42sec seconds. However, the song finishes to the end. I'm trying to make the audio file a sample of 30sec. So it should start at 42sec and end at 1min and 12sec.
Would appreciate any help thanks.
Every time your audio sample starts playing, you can create a Timer object which will make your player stop in a given amount of time.
var audioPlayer = AVAudioPlayer()
var timer: Timer?
func prepareMusic() {
....
// Your code to start playing sample
audioPlayer.currentTime = 42
audioPlayer.play()
// Here we are stopping previous timer if there was any, and creating new one for 30 seconds. It will make player stop.
timer?.invalidate()
timer = Timer(fire: Date.init(timeIntervalSinceNow: 30), interval: 0, repeats: false) { (timer) in
if self.audioPlayer.isPlaying {
self.audioPlayer.stop()
}
}
RunLoop.main.add(timer!, forMode: .defaultRunLoopMode)
}
func musicButton(sender: UIButton) {
....
// If sample is stopped by user — stop timer as well
if audioPlayer.isPlaying {
audioPlayer.stop()
timer?.invalidate()
}
}
There is one more edge case I can think of — if you hide/close view controller, you might also want to stop that timer.
override func viewWillDisappear(_ animated: Bool) {
timer?.invalidate()
}
I have a sliderValueChange function which updates a UILabel's text. I want for it to have a time limit until it clears the label's text, but I also want this "timed clear" action to be cancelled & restarted or delayed whenever the UISlider is moved within the time limit before the "timed clear" action takes place.
So far this is what I have:
let task = DispatchWorkItem {
consoleLabel.text = ""
}
func volumeSliderValueChange(sender: UISlider) {
task.cancel()
let senderValue = String(format: "%.2f", sender.value)
consoleLabel.text = "Volume: \(senderValue)"
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 3, execute: task)
}
Obviously, this approach does not work, since cancel() apparently cannot be reversed.. (or at least I don't know how). I also don't know how to start a new task at the end of this function which will be cancelled if the function is recalled..
Am I going about this the wrong way? Is there something I am overlooking to make this work?
Use a timer:
weak var clearTimer: Timer?
And:
override func viewDidLoad() {
super.viewDidLoad()
startClearTimer()
}
func startClearTimer() {
clearTimer = Timer.scheduledTimer(
timeInterval: 3.0,
target: self,
selector: #selector(clearLabel(_:)),
userInfo: nil,
repeats: false)
}
func clearLabel(_ timer: Timer) {
label.text = ""
}
func volumeSliderValueChange(sender: UISlider) {
clearTimer?.invalidate() //Kill the timer
//do whatever you need to do with the slider value
startClearTimer() //Start a new timer
}
The problem is that you are cancelling the wrong thing. You don't want to cancel the task; you want to cancel the countdown which you got going when you said asyncAfter.
So use a DispatchTimer or an NSTimer (now called a Timer in Swift). Those are counters-down that can be cancelled. And then you can start counting again.
I have just started to learn swift 2 and I am testing a few things in an Xcode 'playground'. When a create an instance of the 'pyx' (below) I am not seeing the console output I would expect. I am sure I have made a silly mistake but after staring at it for a while I cannot figure it out.
class zxy {
var gameTimer = NSTimer()
var counter = 0
init() {
gameTimer = NSTimer (timeInterval: 1, target: self, selector: "Run:", userInfo: nil, repeats: true)
}
func Run(timer : NSTimer) {
while(counter < 10){
print(counter)
counter++
}
timer.invalidate()
}
}
Thanks in advanced.
You have 2 problems with your code. As #glenstorey points out in his answer, you need to call the method scheduledTimerWithTimeInterval:target:selector:userInfo:repeats:, not the init method you're calling.
EDIT:
As #DanBeauleu says in his comment to my answer, the call would look like this in Swift:
NSTimer.scheduledTimerWithTimeInterval(
1,
target: self,
selector: "Run:",
userInfo: nil,
repeats: true)
The second problem is your Run method.
You don't want a while loop. That will repeat 10 times in a tiny fraction of a second the first time the timer fires, then invalidate the timer.
Your timer method needs to be changed like this:
func Run(timer : NSTimer)
{
if counter < 10
{
print(counter)
counter++
}
else
{
timer.invalidate()
}
}
(BTW, by strong convention, method/function names should start with a lower-case letter, so your Run function should be named run instead.)
You've created a NSTimer object, but that doesn't start the timer - just gets it ready to go. Use scheduledTimerWithTimeInterval to create and start the timer.