React Native Expo: Fetch geolocation in background using Task Manager

[anantshukla]

I have been working on a react native application where I have to fetch the geolocation at an interval of 10secs and update it to a server. I was able to do the same when the emulator was active/ in the foreground.

However, when the app is minimized, it doesn’t work. I tried using expo task manager but the function doesn’t seem to run when backgrounded.

What is the error here? I have attached my code and output.

I am using android 11 using an emulator and personal device, expo-cli: 3.28.1, sdk: 37.0.12

Here is my code:

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

//Navigator
import Navigator from './routing/Routing';

const Main = () => {
  const [gpsLatitude, setgpsLatitude] = useState(null);
  const [gpsLongitude, setgpsLongitude] = useState(null);
  const [batteryLevel, setBatteryLevel] = useState(null);

  useEffect(() => {
    (async () => await _askForLocationPermission())();

    const interval = setInterval(() => {
      uploadDataAtInterval();
    }, 10000);
    return () => clearInterval(interval);
  });

  const backgroundLocationFetch = async () => {
    const { status } = await Location.requestPermissionsAsync();
    if (status === 'granted') {
      console.log('cmon dance with me!')
      await Location.startLocationUpdatesAsync('FetchLocationInBackground', {
        accuracy: Location.Accuracy.Balanced,
        timeInterval: 10000,
        distanceInterval: 1,
        foregroundService: {
          notificationTitle: 'Live Tracker',
          notificationBody: 'Live Tracker is on.'
        }
      });
    }
  }


  const _askForLocationPermission = async () => {
    (async () => {
      let { status } = await Location.requestPermissionsAsync();
      if (status !== 'granted') {
        setgpsErrorMsg('Permission to access location was denied');
      }
    })();
  };

  const uploadDataAtInterval = async () => {
      console.log('upload using axios');
      
  }

  const getGPSPosition = async () => {
    let location = await Location.getCurrentPositionAsync({accuracy:Location.Accuracy.High});
    setgpsLatitude(location.coords.latitude);
    setgpsLongitude(location.coords.longitude);
  }


  backgroundLocationFetch();

  return(
    <Navigator />
  )
};

TaskManager.defineTask('FetchLocationInBackground', ({ data, error }) => {
  if (error) {
    console.log("Error bg", error)
    return;
  }
  if (data) {
    const { locations } = data;
    console.log("BGGGG->", locations[0].coords.latitude, locations[0].coords.longitude);
  }
});

export default Main;

Output:

BGGGG 12.88375 80.08169
BGGGG 12.88375 80.08169
App: Not logged on now false  //at every 10secs
App: Not logged on now false
App: Not logged on now false
App: Not logged on now false
App: Not logged on now false
App: Not logged on now false