Interface Geofence

ℹ️ Note:

• Native iOS & Android API support only circular geofences, however the plugin does implement a custom mechanism for handling Polygon Geofences; see vertices.
• The minimum reliable radius is 200 meters.
• The native geofencing API for both iOS and Android require the user authorize locationAuthorizationRequest Always — When in Use will not work.

Adding a single geofence with addGeofence.

example

BackgroundGeolocation.addGeofence({
  identifier: "Home",
  radius: 200,
  latitude: 45.51921926,
  longitude: -73.61678581,
  notifyOnEntry: true,
  notifyOnExit: true,
  extras: {
    route_id: 1234
  }
}).then((success) => {
  console.log("[addGeofence] success");
}).catch((error) => {
  console.log("[addGeofence] FAILURE: ", error);
});

Adding multiple geofences with addGeofences.

example

await BackgroundGeolocation.addGeofences([{
  identifier: "Home",
  radius: 200,
  latitude: 45.51921926,
  longitude: -73.61678581,
  notifyOnEntry: true,
}, {
  identifier: "Work",
  radius: 200,
  latitude: 45.61921927,
  longitude: -73.71678582,
  notifyOnEntry: true
}]);
console.log("[addGeofences] success");

ℹ️ Note: Adding a geofence having an identifier which already exists within the SDK geofence database will cause the previous record to be destroyed and the new one inserted.

---

Listening for Geofence Events

Listen to geofence events with BackgroundGeolocation.onGeofence.

example

// Listen for geofence events.
BackgroundGeolocation.onGeofence(geofence => {
  console.log("[geofence] ", geofence.identifier, geofence.action);
});

---

Polygon Geofencing

The Background Geolocation SDK supports Polygon Geofences (Geofences of any shape). See API docs vertices.

• ℹ️ Polygon Geofencing is sold as a separate add-on (fully functional in DEBUG builds).

---

Infinite Geofencing

The Background Geolocation SDK contains unique and powerful Geofencing features that allow you to monitor any number of circular geofences you wish (thousands even), in spite of limits imposed by the native platform APIs (20 for iOS; 100 for Android).

The SDK achieves this by storing your geofences in its database, using a geospatial query to determine those geofences in proximity (geofenceProximityRadius), activating only those geofences closest to the device's current location (according the limit imposed by the corresponding platform).

• When the device is determined to be moving, the plugin periodically queries for geofences within the geofenceProximityRadius (eg. every minute) using the latest recorded location. This geospatial query is very fast, even with tens-of-thousands geofences in the database.
• The SDK enforces a minimum geofenceProximityRadius of 1000 meters.
• In the following image, the green geofences within geofenceProximityRadius are actively monitored. The grey geofences outside geofenceProximityRadius still exist within the SDK's database but are not actively being monitored.

---

Listening for changes in the actively-monitored set-of-geofences.

As the SDK periodically queries for geofences within the geofenceProximityRadius, you can listen for changes in the actively-monitored geofences using the event onGeofencesChange. This event will let you know those geofences which have begun to be actively monitored (GeofencesChangeEvent.on) in addition to those which just ceased to be actively monitored (GeofencesChangeEvent.off).

example

BackgroundGeolocation.onGeofencesChange((event) => {
  let on = event.on;     //<-- new geofences activated.
  let off = event.off; //<-- geofences that were just de-activated.

  // Create map circles
  on.forEach((geofence) => {
    createGeofenceMarker(geofence)
  });

  // Remove map circles
  off.forEach((identifier) => {
    removeGeofenceMarker(identifier);
  });
});

⚠️ Note:

• When all geofences have been removed, the GeofencesChangeEvent will provide empty lists for both GeofencesChangeEvent.on & GeofencesChangeEvent.off.

---

Removing Geofences

Once a geofence has been inserted into the SDK's database using addGeofence or addGeofences, they will be monitored forever (as long as the plugin remains State.enabled == true). If you've configured stopOnTerminate false and startOnBoot true, geofences will continue to be monitored even if the application is terminated or device rebooted. To cease monitoring a geofence or geofences, you must remove them from the SDK's database (or call BackgroundGeolocation.stop).

• Removing a single geofence by identifier with removeGeofence:

example

BackgroundGeolocation.removeGeofence("HOME").then(success => {
  console.log("[removeGeofence] success");
})

• Removing all geofences with removeGeofences:

example

BackgroundGeolocation.removeGeofences().then(success => {
  console.log("[removeGeofences] all geofences have been destroyed");
})

---

Querying Geofences

Use the method getGeofences to retrieve the entire Array of Geofence stored in the SDK's database.

example

BackgroundGeolocation.getGeofences().then(geofences => {
  console.log("[getGeofences] ", geofences);
})

---

Monitoring only geofences

The BackgroundGeolocation SDK allows you to optionally monitor only geofences without constant location-tracking. To engage geofences-only mode, use the method startGeofences instead of start.

Use option Config.geofenceModeHighAccuracy:true to improve the responsiveness of geofence events.

example

BackgroundGeolocation.onGeofence(geofence => {
  console.log("[geofence] ", geofence);
})

BackgroundGeolocation.ready({
  url: "http://your.server.com/geofences",
  autoSync: true,
  geofenceModeHighAccuracy: true   // <-- consumes more power; default is false.
}, state => {
  // engage geofences-only mode:
  BackgroundGeolocation.startGeofences();
})

Toggling between tracking-modes start and startGeofences

The SDK can easily be toggled between State.trackingMode simply by executing the corresponding start or startGeofences methods.

example

// Listen to geofence events
BackgroundGeolocation.onGeofence(geofence => {
  console.log("[geofence] ", geofence);
  if (geofence.identifier == "DANGER_ZONE") {
    if (geofence.action == "ENTER") {
      // Entering the danger-zone, we want to aggressively track location.
      BackgroundGeolocation.start();
    } else if (geofence.action == "EXIT") {
      // Exiting the danger-zone, we resume geofences-only tracking.
      BackgroundGeolocation.startGeofences();
    }
  }
})

// Add a geofence.
BackgroundGeolocation.addGeofence({
  identifier: "DANGER_ZONE",
  radius: 1000,
  latitude: 45.51921926,
  longitude: -73.61678581,
  notifyOnEntry: true,
  notifyOnExit: true,
})

// Ready the plugin.
BackgroundGeolocation.ready({
  desiredAccuracy: BackgroundGeolocation.DESIRED_ACCURACY_HIGH,
  distanceFilter: 10,
  url: "http://your.server.com/locations",
  autoSync: true
}, state => {
  BackgroundGeolocation.startGeofences();
})