How do you manage background geolocation without the app being killed?

Short answer

Register a background task with TaskManager and expo-location, configure the activity type and update distance, and obtain explicit ACCESS_BACKGROUND_LOCATION permission.

Explanation

Both operating systems impose strict limits on location tracking while the screen is asleep to prevent spying and save power. Android requires a persistent foreground service notification telling the user that the app is tracking location, while iOS requires the precise reason to be declared in UIBackgroundModes.

Code example

import * as TaskManager from 'expo-task-manager';
import * as Location from 'expo-location';

const LOCATION_TASK_NAME = 'background-location-task';

TaskManager.defineTask(LOCATION_TASK_NAME, ({ data, error }) => {
  if (error) return;
  if (data) {
    const { locations } = data as any;
    console.log("Background location:", locations);
  }
});

// Start tracking:
await Location.startLocationUpdatesAsync(LOCATION_TASK_NAME, {
  accuracy: Location.Accuracy.Balanced,
  distanceInterval: 50, // Update only every 50 meters
  showsBackgroundLocationIndicator: true,
});

Common mistakes

• Using highest location accuracy at all times, draining the entire phone battery in under two hours.

Follow-up questions

• How do you manage local and remote push notifications and their tokens?

Sources

• Expo docs — Location
• Expo docs — TaskManager