useLocation

GPS position tracking with three-branch permission handling.

useLocation

Source: hooks/useLocation.ts (102 lines)

The useLocation hook manages GPS position tracking with a three-branch permission handling strategy that adapts to the user’s current permission state.

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Permission State Machine

The hook handles three distinct permission states:

getForegroundPermissionsAsync()
    │
    ├── CASE A: status === "granted"
    │       → Fetch location immediately
    │
    ├── CASE B: status !== "granted" AND canAskAgain === true
    │       → Show system permission dialog
    │       → If granted, fetch location
    │
    └── CASE C: status !== "granted" AND canAskAgain === false
            → Permission permanently blocked
            → Show Alert with "Open Settings" button
            → Deep-link to Android Settings via Linking.openSettings()

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Location Fetch

When permission is granted, the hook fetches the current position with high accuracy:

const location = await Location.getCurrentPositionAsync({
  accuracy: Location.Accuracy.High,
});

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Callback Pattern

The requestLocation function accepts an optional onSuccess callback, allowing callers to run additional logic (like animating the map camera) immediately after coordinates are available:

const coords = await requestLocation((coords) => {
  mapRef.current?.animateCamera({ center: coords });
});

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Return Value

Field	Type	Purpose
hasPermission	boolean or null	null = not yet checked, true = granted, false = denied
currentLocation	LocationCoords or null	Latest GPS coordinates
isLocating	boolean	True while a position request is in flight
requestLocation	function	Triggers the permission check and location fetch

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LocationCoords Type

interface LocationCoords {
  latitude: number;
  longitude: number;
}