Background Geolocation

A Capacitor plugin that lets you receive geolocation updates even while the app is backgrounded. Only iOS and Android platforms are supported.

Usage

import {registerPlugin} from "@capacitor/core";
const BackgroundGeolocation = registerPlugin("BackgroundGeolocation");

// To start listening for changes in the device's location, add a new watcher.
// You do this by calling 'addWatcher' with an options object and a callback. A
// Promise is returned, which resolves to the callback ID used to remove the
// watcher in the future. The callback will be called every time a new location
// is available. Watchers can not be paused, only removed. Multiple watchers may
// exist simultaneously.
BackgroundGeolocation.addWatcher(
    {
        // If the "backgroundMessage" option is defined, the watcher will
        // provide location updates whether the app is in the background or the
        // foreground. If it is not defined, location updates are only
        // guaranteed in the foreground. This is true on both platforms.

        // On Android, a notification must be shown to continue receiving
        // location updates in the background. This option specifies the text of
        // that notification.
        backgroundMessage: "Cancel to prevent battery drain.",

        // The title of the notification mentioned above. Defaults to "Using
        // your location".
        backgroundTitle: "Tracking You.",

        // Whether permissions should be requested from the user automatically,
        // if they are not already granted. Defaults to "true".
        requestPermissions: true,

        // If "true", stale locations may be delivered while the device
        // obtains a GPS fix. You are responsible for checking the "time"
        // property. If "false", locations are guaranteed to be up to date.
        // Defaults to "false".
        stale: false,

        // The minimum number of metres between subsequent locations. Defaults
        // to 0.
        distanceFilter: 50,
        interval: 1000,
    },
    function callback(location, error) {
        if (error) {
            if (error.code === "NOT_AUTHORIZED") {
                if (window.confirm(
                    "This app needs your location, " +
                    "but does not have permission.\n\n" +
                    "Open settings now?"
                )) {
                    // It can be useful to direct the user to their device's
                    // settings when location permissions have been denied. The
                    // plugin provides the 'openSettings' method to do exactly
                    // this.
                    BackgroundGeolocation.openSettings();
                }
            }
            return console.error(error);
        }

        return console.log(location);
    }
).then(function after_the_watcher_has_been_added(watcher_id) {
    // When a watcher is no longer needed, it should be removed by calling
    // 'removeWatcher' with an object containing its ID.
    BackgroundGeolocation.removeWatcher({
        id: watcher_id
    });
});

// The location object.
{
    // Longitude in degrees.
    longitude: 131.723423719132,
    // Latitude in degrees.
    latitude: -22.40106297456,
    // Radius of horizontal uncertainty in metres, with 68% confidence.
    accuracy: 11,
    // Metres above sea level (or null).
    altitude: 65,
    // Vertical uncertainty in metres, with 68% confidence (or null).
    altitudeAccuracy: 4,
    // Deviation from true north in degrees (or null).
    bearing: 159.60000610351562,
    // True if the location was simulated by software, rather than GPS.
    simulated: false,
    // Speed in metres per second (or null).
    speed: 23.51068878173828,
    // Time the location was produced, in milliseconds since the unix epoch.
    time: 1562731602000
}

// If you just want the current location, try something like this. The longer
// the timeout, the more accurate the guess will be. I wouldn't go below about
// 100ms.
function guess_location(callback, timeout) {
    let last_location;
    BackgroundGeolocation.addWatcher(
        {
            requestPermissions: false,
            stale: true
        },
        function (location) {
            last_location = location || undefined;
        }
    ).then(function (id) {
        setTimeout(function () {
            callback(last_location);
            Plugins.BackgroundGeolocation.removeWatcher({id});
        }, timeout);
    });
}

Typescript support

import {BackgroundGeolocationPlugin} from "@nerdynaga/capacitor-background-geolocation";
const BackgroundGeolocation = registerPlugin<BackgroundGeolocationPlugin>("BackgroundGeolocation");

Installation

npm install @nerdynaga/capacitor-background-geolocation
npx cap update

iOS

Add the following keys to Info.plist.:

<dict>
  ...
  <key>NSLocationWhenInUseUsageDescription</key>
  <string>We need to track your location</string>
  <key>NSLocationAlwaysAndWhenInUseUsageDescription</key>
  <string>We need to track your location while your device is locked.</string>
  <key>UIBackgroundModes</key>
  <array>
    <string>location</string>
  </array>
  ...
</dict>

Android

Set the the android.useLegacyBridge option to true in your Capacitor configuration. This prevents location updates halting after 5 minutes in the background. See https://capacitorjs.com/docs/config and https://github.com/nerdynaga/background-geolocation/issues/89.

On Android 13+, the app needs the POST_NOTIFICATIONS runtime permission to show the persistent notification informing the user that their location is being used in the background. You may need to request this permission from the user, this can be accomplished using the @capacitor/local-notifications plugin.

If your app forwards location updates to a server in real time, be aware that after 5 minutes in the background Android will throttle HTTP requests initiated from the WebView. The solution is to use a native HTTP plugin such as CapacitorHttp. See https://github.com/nerdynaga/background-geolocation/issues/14.

Configration specific to Android can be made in strings.xml:

<resources>
    <!--
        The channel name for the background notification. This will be visible
        when the user presses & holds the notification. It defaults to
        "Background Tracking".
    -->
    <string name="capacitor_background_geolocation_notification_channel_name">
        Background Tracking
    </string>

    <!--
        The icon to use for the background notification. Note the absence of a
        leading "@". It defaults to "mipmap/ic_launcher", the app's launch icon.

        If a raster image is used to generate the icon (as opposed to a vector
        image), it must have a transparent background. To make sure your image
        is compatible, select "Notification Icons" as the Icon Type when
        creating the image asset in Android Studio.
    -->
    <string name="capacitor_background_geolocation_notification_icon">
        drawable/ic_tracking
    </string>
</resources>

Changelog

v1.0.0

• Initial release.