background_fetch 0.0.1

Periodic callbacks in the background for both iOS and Android. Includes Android Headless implementation.

example/lib/main.dart

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

import 'package:background_fetch/background_fetch.dart';

/// This "Headless Task" is run when app is terminated.
void backgroundFetchHeadlessTask() async {
  print('[BackgroundFetch] Headless event received.');
  BackgroundFetch.finish();
}

void main() {
  // Enable integration testing with the Flutter Driver extension.
  // See https://flutter.io/testing/ for more info.
  runApp(new MyApp());

  // Register to receive BackgroundFetch events after app is terminated.
  // Requires {stopOnTerminate: false, enableHeadless: true}
  BackgroundFetch.registerHeadlessTask(backgroundFetchHeadlessTask);
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  bool _enabled = true;
  int _status = 0;
  List<DateTime> _events = [];

  @override
  void initState() {
    super.initState();
    initPlatformState();
  }

  // Platform messages are asynchronous, so we initialize in an async method.
  Future<void> initPlatformState() async {
    // Configure BackgroundFetch.
    BackgroundFetch.configure(BackgroundFetchConfig(
        minimumFetchInterval: 15,
        stopOnTerminate: false,
        enableHeadless: true,
        forceReload: false
    ), () async {
      // This is the fetch-event callback.
      print('[BackgroundFetch] Event received');
      setState(() {
        _events.insert(0, new DateTime.now());
      });
      // IMPORTANT:  You must signal completion of your fetch task or the OS can punish your app
      // for taking too long in the background.
      BackgroundFetch.finish();
    }).then((int status) {
      print('[BackgroundFetch] SUCCESS: $status');
      setState(() {
        _status = status;
      });
    }).catchError((e) {
      print('[BackgroundFetch] ERROR: $e');
      setState(() {
        _status = e;
      });
    });

    // Optionally query the current BackgroundFetch status.
    int status = await BackgroundFetch.status;
    setState(() {
      _status = status;
    });

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;
  }

  void _onClickEnable(enabled) {
    setState(() {
      _enabled = enabled;
    });
    if (enabled) {
      BackgroundFetch.start().then((int status) {
        print('[BackgroundFetch] start success: $status');
      }).catchError((e) {
        print('[BackgroundFetch] start FAILURE: $e');
      });
    } else {
      BackgroundFetch.stop().then((int status) {
        print('[BackgroundFetch] stop success: $status');
      });
    }
  }

  void _onClickStatus() async {
    int status = await BackgroundFetch.status;
    print('[BackgroundFetch] status: $status');
    setState(() {
      _status = status;
    });
  }
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new Scaffold(
        appBar: new AppBar(
          title: const Text('BackgroundFetch Example', style: TextStyle(color: Colors.black)),
          backgroundColor: Colors.amberAccent,
          brightness: Brightness.light,
          actions: <Widget>[
            Switch(value: _enabled, onChanged: _onClickEnable),
          ]
        ),
        body: Container(
          color: Colors.black,
          child: new ListView.builder(
              itemCount: _events.length,
              itemBuilder: (BuildContext context, int index) {
                DateTime timestamp = _events[index];
                return InputDecorator(
                    decoration: InputDecoration(
                        contentPadding: EdgeInsets.only(left: 10.0, top: 10.0, bottom: 0.0),
                        labelStyle: TextStyle(color: Colors.amberAccent, fontSize: 20.0),
                        labelText: "[background fetch event]"
                    ),
                    child: new Text(timestamp.toString(), style: TextStyle(color: Colors.white, fontSize: 16.0))
                );
              }
          ),
        ),
        bottomNavigationBar: BottomAppBar(
          child: Row(
            children: <Widget>[
              RaisedButton(onPressed: _onClickStatus, child: Text('Status')),
              Container(child: Text("$_status"), margin: EdgeInsets.only(left: 20.0))
            ]
          )
        ),
      ),
    );
  }
}