I have implemented a Timer as detailed in the article below, so that the timer will keep running when i change tabs.
How to implement persistent stopwatch in Flutter?
I have an issue where the Timer "loses" or pauses time, only when not plugged into my computer. When i plug it into my computer, no issues, the emulator runs fine too. I test the flutter timer against a timer on my computer or phone, and after 5mins, they match. But when my phone (Galaxy S9) isn't plugged in, after 5mins of real time, the flutter timer might only be up to 2mins, when i go back into the app the timer is running but the timer wont be what it should be. It doesn't crash or reset, its counting when i get back into the app. I'm finding it hard to debug as when I plug the phone into my computer it seems to work fine! Any ideas?
I had issues with this as well. Things working correctly when running on the Simulator is fools gold. The Timer won't run in the background like you want it to unless you do specific work to keep it running. Here is the official page from Flutter on doing work in the background: https://flutter.dev/docs/development/packages-and-plugins/background-processes
I'll suggest implementing didChangeAppLifecycleState method of the WidgetsBindingObserver and detect when the app goes to the background and when it's back in the foreground. At the point where the app goes into the background, you save the current time e.g (onPauseTime) (you can use SharedPreferences here) and the Duration left on the timer (timerDurationLeft).
When the app is back in the foreground you check if the timer was running before the app entered the background state, if it was, you then check the current time e.g (onResumeTime) and calculate the time difference in seconds (onResumeTime - onPauseTime), using the time difference and the timerDurationLeft you can calculate how much time the timer has left to run and you start/resume the timer from that point or end/set the timer to 0:00 if time has already passed.
P:S Using a background service would be the way to go if you intend to perform some actions in the middle, like set notifications at some point where the timer is almost complete.
Related
My flutter app allows users to time how long they have been working for. I'm using the package stop_watch_timer.
Everything works fine except when the app gets killed in the background, because then I lose the timer value and it goes back to 0. As users are likely to start the timer then put their phone away and work for a while, the app getting killed is a very likely scenario and I need to make sure that this never happens. Another feature that I need in the app is for users to be able to pause and unpause the timer whenever they want.
Here are the solutions I have come up with so far and their problems:
Solution 1: Store the start DateTime on the phone using shared_preferences and calculate the current timer value when app is reopened by simply calculating the duration between start time and DateTime.now(). But then I realised that this does not work if the user had paused and unpaused the timer at some point.
Solution 2: Store the current timer value as a RestorableInt. This works if the timer is on pause when the app gets killed, but does not work if the timer is meant to be running when the app dies.
Any suggestions or ideas??
You should store something like this:
[
{"start":1664027960},
{"pause":1664027975},
{"unpause":1664027979},
{"pause":1664028061},
{"unpause":1664028065},
]
Everytime a user hits the pause button you add the time to the list and store it in the shared_prefs or in a json file. Same for unpausing.
You can then calculate the total ellapsed time.
My app is checking some algorithm in the background, after something like 30 minutes
my application seems to be like close (iphone turn to sleep mode i think). I need the app
to run this algorithm as long as it is in the background.
Do you have any idea how to set this 20 minutes timer to recount by some action?
maybe NSRunloop or something else?
You can't reset this timer or continue to run in the background on a stock OS iPhone (except for a limited amount of time, or if your is legitimately of 3 types, VoIP, audio or GPS).
The user can reset this timer by bringing your app to the foreground, perhaps after a notification or something.
Playing around with Timers, and trying to make them behave right when app is sent to background, killed etc.
Judging by the generated comments in xcode, you should disable/invalidate timers on resignActive/enterBackground events.
However, i havent done that yet, but checked what happens to my timer when i click the home button and then re-enter the app.
I basically have a method in my view that the timer triggers every second:
NSLog(#"workedTimTimerTick workedTime; %#", timeString);
And when i exit the app, the output stops, when i re-enter the app, the output starts again...
Since i'm not doing anything code-wise to the timer on those lifecycle events, how come it stops getting called?
Input appreciated!
Your app is suspended when it enters background mode (Application States and Transitions).
Your timer won't fire when the app is in background and the time spent in background isn't taken into account for the timer delay.
I am developing an iphone app which uses background audio (on an infinite loop) to continue playing after the app has entered the background.
My problem is I want to implement a "sleep timer" which stops playback after a specified period of time.
Is this possible? I have spent an hour looking for a method to do this with no avail.
EDIT: My current thought is to use a lower level API, the Audio Queue Services, and manually re-fill the queue with another instance of the loop during the AudioQueueOutputCallback. If the timer has expired I do not fill the loop. I'm assuming this should work since the documentation says audio callbacks are still fired when an app is playing multitasking background audio. Can anyone think of a better way or a reason why this wouldn't work?
While you queue sound data on the background your app remains fully functional and running as if it was in the foreground (well almost), so yes, you should just write a timer that stops the playback at a given time and it will be fired as expected.
Now to the second question: once you stop queueing things up, your app will be "frozen" until the user manually brings it to the foreground... So what you should do is start queueing audio data from the second file before the first one is done playing, and if you DO need to pause or stop, maybe a solution is to play 0 bytes (silence)?
I'm not actually sure this would be allowed in the App Store. An app is not allowed to execute at all in the background, with the exception of VoIP apps and push notifications.
I have used:
[UIApplication sharedApplication].idleTimerDisabled = YES;
in a number of Apps developed and running under iPhone OS 2.x and never had any problems with it. They were clock apps so needed to run constantly and ignore the iPhone's idle Timer setting.
However, trying to achieve the same with a new App running OS 3.0 (and which needs to be deployed under 3.0 as it uses some 3.0 APIs) I've found the idle Timer to be either ignored or inconsistent.
My App plays music from the iPod library and when the music is playing it auto-locks regardless of the above setting. But once you unlock it, it then doesn't auto-lock again unless you play music again, in which case it locks again after the iPhone auto-lock time setting.
I'm amazed no-one else has come across this as I imagine it would affect a large number of Apps.
Just to clarify:
1. The above code is in ApplicationDidFinishLaunching
2. I know that the phone won't auto-lock when testing from xCode regardless of settings
If anyone has any thoughts I'd be very grateful...
Our app uses the MPMediaPLayer. We also had the idleTimerDisabled=YES code in the ApplicationFinishedLaunching, which works EXCEPT if untethered, and there is already a current nowPlayingItem which is left playing (or unpaused, if paused at app startup). Obviously this is all with the Settings -> General -> Autolock set to some timed value.
By adding idleTimerDisabled=NO, immedately followed by idleTimerDisabled=YES in one of the other bits of code AFTER we had figured out what bit of music we would get playing seemed to solve the problem. Just setting it to YES was insufficient.. and subsequent queries had always indicated the correct value (YES).. so it appears the Apple code ignores the setting of the value IF there is a current piece of music and that is not changed by your code.. but does notice a change of value.
This is all under iOS 3.0.
Even in 2015, using iOS 8.2, this bug is still alive and kicking.
Here's my solution, using XCode 6.2.
iPhone - phone goes to sleep even if idleTimerDisabled is YES
Basically, even now, in 2015, the only way to safely make sure that the device doesn't go to sleep is to repeatedly call a piece of code to keep the device awake.
-(void)callEveryTwentySeconds
{
// DON'T let the device go to sleep during our sync
[[UIApplication sharedApplication] setIdleTimerDisabled:NO];
[[UIApplication sharedApplication] setIdleTimerDisabled:YES];
}
Sounds like a bug, file with Radar - I am not too surprised this has not been seen much as there are probably not a lot of apps that try to lock the screen open and play music.
Having same issue. It does work when the device is plugged in. You can press lock button on top, and my NSTimer fires later and causes a vibrate. However if the device is not plugged in pressing the lock button puts the device to sleep. Any solution would be greatly appreciated.
iCodeblog posted about the idletimer, I said it didn't work, and the person who develops 'cute clock' was nice enough to reply. You have to do a hack, play a 1 second or longer silent sound every 10 or so seconds with NSTimer. This keeps the device awake even if the user hits the lock button.
I develop Seconds - Interval Timer for iPhone and iPod touch and I've had no end of trouble with this. The idea of my app is that people create timers based on a number of intervals where each interval can have it's own playlist or track played.
In iOS3 I had the problem that I couldn't disable the idle timer by just setting idleTimerDisabled = YES. In the end I came up with the same solution as Neil whereby I would periodically set it to NO, then immediately to YES again. This seemed to work.
I'm now updating the app to iOS4 (I know, iOS5 is just around the corner...) and now I have the opposite problem. If the MPMediaPlayer changes track before the idle timer reaches it's limit it gets reset. I've just tested this by creating an interval in my app that was 55 seconds, my auto-lock was set to a minute. At 50 seconds the screen dimmed as it prepared to lock, but at 55 seconds when the music changed it went back to full brightness and then didn't lock as it should.
Overall, the implementation of this seems flakey at best.