Background Location Updates for Flutter (background_location_updates)

A Flutter plugin for getting location updates even when the app is in background, but not killed.

• Native Android, written in Kotlin

• IOS, written in Swift

Please note: Dont't use in production. Currently this flutter plugin is under construction.

Overview

This flutter plugin will request location updates and an additional payload (at the moment to generate a sequence a random 8 digit integer each second). It needs to be started / stopped by the user. As a confirmation a notification will be sent. It will run in fore- and background and automatically stops when app exits.

Screenshot

Installation

1. Add dependency at pubspec.yaml

dependencies:
  flutter:
    sdk: flutter
  background_location_updates:
    git:...[will follow soon]
  permission_handler: ^5.0.1+1  # used for permission handling
  flutter_beep: ^0.2.0          # (optional) for testing purpose
  flutter_map: ^0.10.1+1        # (optional) for testing purpose

2. Add permissions at Android: android/app/src/AndroidManifest.xml

<uses-permission android:name="android.permission.WAKE_LOCK"/>
<uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_BACKGROUND_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

3. Add permissions at IOS: ios/Runner/Info.plist

<key>NSLocationAlwaysUsageDescription</key>
<string>Program requires GPS to track cars and job orders</string>
<key>NSLocationAlwaysAndWhenInUseUsageDescription</key>
<string>Program requires GPS to track cars and job orders</string>
<key>NSLocationWhenInUseUsageDescription</key>
<string>Program requires GPS to track cars and job orders</string>
<key>UIBackgroundModes</key>
<array>
    <string>fetch</string>
    <string>location</string>
    <string>processing</string>
</array>

Usage in your app

1. Add imports (refer example/lib/main.dart)

import 'package:background_location_updates/background_location_updates.dart';

# used for permission handling
import 'package:permission_handler/permission_handler.dart'; 

# (optional) for testing purpose
import 'package:flutter_map/flutter_map.dart';
import 'package:latlong/latlong.dart';
import 'package:flutter_beep/flutter_beep.dart';

2. Permissions (refer example/lib/main.dart)

init() async {
    Map<Permission, PermissionStatus> statuses = await [
        Permission.location,
        Permission.locationAlways,
        Permission.locationWhenInUse,
        Permission.notification
    ].request();
    print(statuses[Permission.location]);
}

3. Configuration (refer example/lib/main.dart)

BackgroundLocationUpdates locationUpdates = new BackgroundLocationUpdates();
  
locationUpdates.configureSettings(
    accuracy: LocationAccuracy.high,
    intervalMilliSecondsAndroid: 1000,
    distanceFilterMeter: 0,
    mockUpDetection: true);

4. Definition of callback for location updates (refer example/lib/main.dart)

BackgroundLocationUpdates locationUpdates = new BackgroundLocationUpdates();

locationUpdates.setCallback((method, args) {
  updateState(method, args);
});

In updateState the following methods/args are available:
"onStatus"/ boolean       - indicates, if the service is running
"onLocation" / Location   - whenever a ew location is delivered
"onData" / int            - whenever a new random 8 digits is delivered

5. The status can also be requested by

 isRunning = await locationUpdates.isRunning();

6. Alternatively to continous updates its also possible to request one single Location / random number

locationUpdates.getLocation();
locationUpdates.getValue();

Implementation Details

Please note: Dont't use in production. Currently this flutter plugin is under construction.

Communication with Native Code: The plugin communicates with the Native Andoid/IOS API via a MethodChannel ("channel"). The communication back is done via the same Methodchannel which calls the callback in Flutter.

Data Handling in IOS: The delivery of all data is also done directly by use of the same MethodChannel (indepandantly if the app operates in foreground or in background).

Data Handling in Android: To enable background operation on an Android device additional native services are launched to deliver all data. The native services communicate via the MethodChannel to an internal receiver ("backgroundReceiver") in Flutter. Finally the backgroundReceiver calls the callback via an internal IsolateNameServer.