Creating a Geolocation Feature in Flutter

Flutter is an open-source mobile application development framework created by Google. It is used to develop applications for Android, iOS, Windows, Mac, Linux, Google Fuchsia, and the web. Flutter is known for its fast development cycles, expressive and flexible UI, and native performance.

One of the great features of Flutter is its ability to incorporate geolocation features. With geolocation, users can track their location in real-time, allowing them to make better decisions, interact with maps, and more. In this tutorial, we’ll cover how to install geolocation and maps into a Flutter project, access the GPS data on the device, display the user’s location on a map, handle background updates, and handle geolocation errors.

Installing Geolocation & Maps into a Flutter Project

The first step to using geolocation and maps in Flutter is to add the relevant packages to your project. To do this, open your pubspec.yaml file and add the following packages:

dependencies:
  flutter:
    sdk: flutter
  # Add the following packages
  geolocator: ^3.1.0
  google_maps_flutter: ^0.5.21+1

Once you’ve added the packages, run flutter packages get in your project’s root directory to fetch and install them.

Accessing the GPS Data on Device

Once the packages are installed, you can start using them in your project. To access the GPS data on the device, you need to use the Geolocator package. The following code snippet shows how to get the user’s current location:

// Get the user's current location
Position position = await Geolocator().getCurrentPosition(
  desiredAccuracy: LocationAccuracy.best
);

The getCurrentPosition method takes a desiredAccuracy parameter, which specifies the accuracy of the location data that is returned. The available accuracy levels are best, high, medium, and low.

Displaying the User's Location on a Map

Once you have the user’s current location, you can use the GoogleMaps package to display it on a map. To do this, you need to create a GoogleMap widget and pass it the user’s coordinates:

GoogleMap(
  initialCameraPosition: CameraPosition(
    target: LatLng(position.latitude, position.longitude),
    zoom: 14.0
  ),
  markers: Set.from(markers)
)

The initialCameraPosition property specifies the initial position of the camera on the map. The target property is used to specify the coordinates of the user’s location, while the zoom property is used to specify the zoom level of the map. The markers property is used to specify the markers that should be displayed on the map.

Handling Background Updates

The Geolocator package allows you to track the user’s location in the background. To do this, you need to call the getPositionStream method:

StreamSubscription<Position> positionStream = Geolocator()
  .getPositionStream(LocationOptions(
    accuracy: LocationAccuracy.best,
    distanceFilter: 10
  ))
  .listen((Position position) {
    // Handle the position update
  });

The getPositionStream method takes a LocationOptions object, which contains the desired accuracy and distance filter. The distanceFilter property specifies the minimum distance (in meters) the device must move before the listen callback is triggered.

Handling Geolocation Errors

When using geolocation, it’s important to handle errors gracefully. The Geolocator package provides a GeolocationStatus enum, which contains a list of possible errors. You can use this enum to check the status of the geolocation request:

if (Geolocator().checkGeolocationPermissionStatus() ==
    GeolocationStatus.denied) {
  // Handle the denied permission
}

The checkGeolocationPermissionStatus method checks the status of the geolocation request and returns one of the GeolocationStatus enum values.

Conclusion

In this tutorial, we’ve covered how to install geolocation and maps into a Flutter project, access the GPS data on the device, display the user’s location on a map, handle background updates, and handle geolocation errors. With these features, you can create powerful location-aware applications with Flutter.