Reading GPS Location with expo-location
Request foreground location permission, get the current coordinates with getCurrentPositionAsync, and display latitude and longitude on screen.
Reading GPS Location with expo-location is a free React Native Academy lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the React Native Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What Is expo-location?
expo-location provides an API to read the device's geographic position using GPS, Wi-Fi triangulation, and cell tower data. It works on both iOS and Android without writing native code. You can get a one-time position fix, watch the location as the user moves, or geocode an address to coordinates and vice versa.
Installing expo-location
Use the Expo install command to get the SDK-compatible version of expo-location. In managed Expo projects, the native module is linked automatically. For bare React Native projects, you must also run pod install on iOS and update AndroidManifest.xml with the location permission declarations.
npx expo install expo-locationRequesting Foreground Location Permission
Location access requires explicit user permission. Call Location.requestForegroundPermissionsAsync() to ask for permission to read location while the app is in the foreground. Check the status field of the returned object — only proceed if it equals 'granted'. The hook version Location.useForegroundPermissions() simplifies this in functional components.
import * as Location from 'expo-location';
const [permission, requestPermission] = Location.useForegroundPermissions();
if (!permission) return <ActivityIndicator />;
if (!permission.granted) {
return (
<View>
<Text>Location access is needed to show your position.</Text>
<Button title='Allow Location' onPress={requestPermission} />
</View>
);
}Getting the Current Position Once
Location.getCurrentPositionAsync() performs a single GPS fix and returns a LocationObject containing coords.latitude, coords.longitude, coords.accuracy (in meters), and a timestamp. Use this for one-time lookups like 'find nearby restaurants' where you do not need continuous tracking.
const [location, setLocation] = React.useState(null);
async function fetchLocation() {
const loc = await Location.getCurrentPositionAsync({
accuracy: Location.Accuracy.Balanced,
});
setLocation(loc);
console.log('Lat:', loc.coords.latitude);
console.log('Lng:', loc.coords.longitude);
console.log('Accuracy:', loc.coords.accuracy, 'meters');
}Accuracy Levels
expo-location provides several accuracy presets via Location.Accuracy. Use Lowest or Low for coarse location with minimal battery impact, Balanced for general use, and High or BestForNavigation when you need precise GPS coordinates for turn-by-turn navigation. Higher accuracy drains battery faster, so choose appropriately for your use case.
// Coarse — fast, low battery, uses Wi-Fi/cell
Location.Accuracy.Lowest // ~3 km
Location.Accuracy.Low // ~1 km
Location.Accuracy.Balanced // ~100 m — good default
// Precise — uses GPS, more battery
Location.Accuracy.High // ~10 m
Location.Accuracy.Highest // ~1 m
Location.Accuracy.BestForNavigation // highest + sensorsWatching the Location Continuously
Location.watchPositionAsync starts a subscription that calls a callback every time the device's position changes by a specified distance or time interval. It returns a subscription object with a remove() method. Always call remove() in a useEffect cleanup function to stop tracking when the component unmounts and save battery.
useEffect(() => {
let subscription: Location.LocationSubscription;
async function startWatching() {
subscription = await Location.watchPositionAsync(
{
accuracy: Location.Accuracy.High,
distanceInterval: 10, // update every 10 meters
timeInterval: 5000, // or every 5 seconds
},
(loc) => setLocation(loc)
);
}
startWatching();
return () => subscription?.remove(); // cleanup on unmount
}, []);Displaying Coordinates on Screen
Once you have a location object, display the coordinates in a human-readable format. Round latitude and longitude to 5-6 decimal places for readability — that corresponds to roughly 1-meter precision. Display the accuracy value so users understand how precise the reading is, especially on devices that cannot get a good GPS fix indoors.
export default function LocationDisplay() {
const [location, setLocation] = React.useState(null);
// ... permission check and fetch ...
if (!location) return <Button title='Get Location' onPress={fetchLocation} />;
return (
<View>
<Text>Latitude: {location.coords.latitude.toFixed(6)}</Text>
<Text>Longitude: {location.coords.longitude.toFixed(6)}</Text>
<Text>Accuracy: {location.coords.accuracy?.toFixed(0)} m</Text>
</View>
);
}Reverse Geocoding: Coordinates to Address
Location.reverseGeocodeAsync converts latitude and longitude coordinates into a human-readable address. It returns an array of LocationGeocodedAddress objects with fields like street, city, region, country, and postalCode. Use the first result — it is the most likely match for the given coordinates.
async function getAddress(latitude: number, longitude: number) {
const results = await Location.reverseGeocodeAsync({ latitude, longitude });
if (results.length > 0) {
const addr = results[0];
return [addr.street, addr.city, addr.region, addr.country]
.filter(Boolean)
.join(', ');
}
return 'Unknown location';
}Forward Geocoding: Address to Coordinates
Location.geocodeAsync converts a text address into latitude and longitude. This is useful for features like 'search nearby' where users type a location name. The function returns an array of results (multiple matches are possible for ambiguous addresses) each containing latitude, longitude, and altitude.
async function searchAddress(address: string) {
const results = await Location.geocodeAsync(address);
if (results.length > 0) {
const { latitude, longitude } = results[0];
console.log('Coordinates:', latitude, longitude);
return { latitude, longitude };
}
return null;
}Handling Location Errors
Location requests can fail when the user is indoors, when the device's GPS is disabled, or on simulators that do not have a simulated location set. Wrap location calls in try-catch and show a fallback UI. Check Location.hasServicesEnabledAsync() before requesting a position to detect when the device's location services are turned off in system settings.
async function fetchLocationSafe() {
const enabled = await Location.hasServicesEnabledAsync();
if (!enabled) {
Alert.alert('Location Off', 'Please enable Location Services in Settings.');
return;
}
try {
const loc = await Location.getCurrentPositionAsync({
accuracy: Location.Accuracy.Balanced,
});
setLocation(loc);
} catch (err) {
Alert.alert('Error', 'Could not get your location. Please try again.');
}
}Background Location Tracking
Tracking location when the app is in the background requires background location permission (requestBackgroundPermissionsAsync) and a background task defined with expo-task-manager. This is only needed for apps like fitness trackers or delivery apps. Apple and Google have strict review requirements for apps that use background location, so only request it if the feature is core to your app.
Quick Check
Test your understanding of React Native Mobile Development concepts from this lesson.
Lesson Recap
In this lesson you learned: requestForegroundPermissionsAsync must be called and granted before any location reading is possible, getCurrentPositionAsync performs a one-time position fix while watchPositionAsync tracks continuous movement, and reverseGeocodeAsync converts coordinates to a human-readable address. Next up we explore scheduling local notifications.
Frequently asked questions
Is the “Reading GPS Location with expo-location” lesson free?
Yes — the full text of “Reading GPS Location with expo-location” is free to read here on the web, and the React Native Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the React Native Academy course, upgrade to CoddyKit PRO.
What will I learn in “Reading GPS Location with expo-location”?
Request foreground location permission, get the current coordinates with getCurrentPositionAsync, and display latitude and longitude on screen. You practise React Native Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start React Native Academy?
No prior experience is required. React Native Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Reading GPS Location with expo-location” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this React Native Academy lesson?
Yes. Every React Native Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Camera Access with expo-camera
- Reading GPS Location with expo-location
- Scheduling Local Notifications
- Handling Permissions Gracefully