Hi I instantiated an isolate for my data layer above my main app, above runApp()
I wonder what will happen when the app is minimised, will the isolate be closed. Do isolates time out anyway...
Has anyone got experience of this in a live app?
As from Flutter's happy recommendeations page:
There are a of couple ways to incorporate background processing into your mobile app. One way is through a Dart isolate. With a Dart
isolate, you can create a separate thread to run tasks concurrently in
the background.
Another way to incorporate background processing is through the
WorkManager plugin. With this plugin, you can enable persistent
headless execution of Dart code. Your tasks remain scheduled through
app restarts and system reboots.
so the answer is yes, you can achieve running dart code in the background with Dart isolates, but consider also using the workManager package.
I tested the situation proposed, and the isolates were working(simply setup a timer which logs some random message to console) even if app is minimised. If the app is killed by user or by OS, isolates will be killed as well. And yes you can spawn an isolate before runApp(). If the isolate is required to return some data to the main isolate, I recommend making the main() function async and wait(await) for the completion. Flutter will not render the UI until everything before runApp() is completed without error.
Related
I have a question about how best to structure a background process in a Flutter mobile app that can be triggered in a number of ways.
This background process has to run a web API call, or series of web API calls. The process will take 1 to 5 seconds to complete.
I want the process to be initiated when any of the following occurs:
When the app first starts
When the user initiates a 'refresh' by clicking on a button in the UI
Every hour
Any suggestions on how to structure this in a Flutter app?
You should take a look at this package: https://pub.dev/packages/flutter_background_service
It can run code in background and/or in foreground either on iOs and Android.
Background and foreground are run in isolate, so you should use mechanism provide by package to exchange data between your application and background/foreground.
I am trying to create a flutter app that sends notification every time there is new entry in stream builder, it works fine when the app is on or opened but I want it to work and receive notification even when it is not opened , I have used workmanager to make the task work in background but it is not working ...the code for it can be found here code
Flutter apps by nature are supposed to run on a UI thread or foreground. The background tasks you are asking for are features disclosed by each individual platforms.
In case of Android, you can create a a Background Service to accomplish the tasks you need to perform when application is closed. The link to the bacground service is as follows: Creating a Background Service
In case of iOS, see this link for creating a background task. Other platform implementation will be as like above, so please have a look into each platform specific background process.
UPDATE:
Please have a look into the package Flutter Background Service. This package helps to deal with background tasks setup from flutter side even when app is closed.
NOTE:
Q: Why the service not started automatically?
A: Some android device manufacturers have a custom android os for example MIUI from Xiaomi. You have to deal with that policy.
Q: Service killed by system and not respawn?
A: Try to disable battery optimization for your app.
Actually I was trying to implement background process (fetch data from api) even the app is terminated in my flutter project how can I achieve in both Android & iOS platforms.
Have you ever wanted to execute Dart code in the background—even if your app wasn’t the currently active app?
The mechanism for this feature involves setting up an isolate.
Isolates are Dart’s model for multithreading, though an isolate
differs from a conventional thread in that it doesn’t share memory
with the main program. You’ll set up your isolate for background
execution using callbacks and a callback dispatcher.
Example
but if you want do that when app terminated, you will have to wakeup app through Workmanager or some another approach like sending firebase push notification or wakeup app in scheduled time with flutter alarm manager or something like that
Is it possible to use connectivity plugin in background process?
I don't know how to call dart code in background there is little about this in docs.
I need this functionality to sync offline data with backend whenever there is a connection wether app is in foreground or background and app is in killed state like the way Whatsapp syncs messages.
You can use existing plugins for background execution (on android & ios usually in a roughly 15 minute interval)
https://pub.dev/packages/background_fetch
There is also a article dedicated to using isolates for background executions
https://flutter.dev/docs/development/packages-and-plugins/background-processes
https://medium.com/flutter/executing-dart-in-the-background-with-flutter-plugins-and-geofencing-2b3e40a1a124
I need to run a dart code for each 30s even if the application is closed. Is it possible?
Some workarounds suguested is use AlarmManager for Android, but, I not found solution for iOS.
There's no good article on how to implement an isolate to work when the app is closed without running some native code. In total, I have spent 2 full days trying to find a package for this, but nothing exists that works. Flutter_Isolate doesn't run when app is killed and Flutter Workmanager can only do print statements but can't take in any functions or any method call. Ultimately pathetic and very annoying. The only solution seems is to write native code to handle background tasks when app is closed. Shame on flutter.
Yes, it is possible. You can run Flutter in background.
In Flutter, you can execute Dart code in the background.
The mechanism for this feature involves setting up an isolate.
Isolates are Dart’s model for multithreading, though an isolate
differs from a conventional thread in that it doesn’t share memory
with the main program. You’ll set up your isolate for background
execution using callbacks and a callback dispatcher.
Source: Background processes
Yes its possible you can run a flutter app in background even if the app is closed using the following package:
https://pub.dev/packages/flutter_background_service
try using these two packages
https://pub.dev/packages/workmanager
https://pub.dev/packages/flutter_background_service