But when pressing the back button, the Observatory shows no running Isolate. The Observatory will show an active Flutter app Isolate running. You can test that by connecting to the Dart Observatory when switching between apps, or turning of the screen. But when pressing the back button while the Flutter app has the focus, the Activity gets destroyed, and with it the Dart isolate. When switching to another app, or when pressing the power button to turn of the screen the timer continues to run. Switching between apps, pressing power or back button Flutter app resumed (_timerCounter value is 0 again).This is the moment where the FlutterActivity gets destroyed and the Dart VM Isolate as well. Pressed back button on phone (_timerCounter value not changed).Unlocked phone, Flutter app resumed (_timerCounter value 7).Pressed power button, display turned off (_timerCounter value 4).Return to Flutter app (_timerCounter value 3).Switch to other app (_timerCounter value 1). I/flutter (28196): LifecycleWatcherState#didChangeAppLifecycleState state=AppLifecycleState.resumedįor the above log output, here are the steps I did: I/flutter (28196): LifecycleWatcherState#didChangeAppLifecycleState state=AppLifecycleState.paused The Observatory debugger and profiler is available at: įor a more detailed help message, press "h" or F1. □ To hot reload your app on the fly, press "r" or F5. I/flutter (28196): _MyHomePageState#constructor, creating new Timer.periodic Launching lib/main.dart on SM N920S in debug mode.īuilding APK in debug mode (android-arm). A text field below the counter will show any AppLifecycleState changes for the Flutter app, you will see corresponding output in the Flutter debug log, e.g.: flutter run When launching the app, the value of _timerCounter is incremented every 3s. Framework revision b339c71523 (6 hours ago), 00:51:32Ĭreate a new Flutter app, and replace the content of lib/main.dart with this code: import 'dart:async' Ĭlass LifecycleWatcher extends StatefulWidget createState() => new _LifecycleWatcherState() Ĭlass _LifecycleWatcherState extends StateĪppLifecycleState initState() dispose() onDeactivate() didChangeAppLifecycleState(AppLifecycleState state).The following code will help you understand the different states of a Flutter app on Android, tested with the these Flutter and Flutter Engine versions: Short answer: no, it's not possible, although I have observed a different behavior for the display going to sleep. If you have other use cases for background code you'd like us to know about, comments are most welcome on that bug! The use-case driving that kind of back-ground code execution is when your app receives a notification, wants to process it using some Dart code without bringing your app to the front. Separately, the more general question of "is it possible to run background Dart code" (without having a FlutterView active on screen), is "not yet". We're working on a system for publishing/sharing service integrations like this so that once one person writes this integration (for say scheduling some future execution of your app) everyone can benefit. This allows them to kill/suspend your app to achieve better power savings and instead have a single highly-efficent shared system service for tracking these notifications/alarms/geofencing, etc.įlutter does not currently provide any wrappers around these OS services out-of-the-box, however it is straighforward to write your own using our platform-services model: For example on iOS you can request that your application be notified/woken at a specific point in the future via UINotificationRequest: Instead mobile operating systems provide apis (like a timer/alarm/notification apis) to call back to your application after a specific time. Overall running code in the background is something discouraged on mobile operating systems.įor example, iOS Documentation discusses background code in greater detail here: Answering the question of how to implement your specific timer case doesn't actually have to do with background code.
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