Permissions — The Right Way

import * as Location from 'expo-location';
import * as Camera from 'expo-camera';
import * as Notifications from 'expo-notifications';
import { Linking, Alert } from 'react-native';

// ---- Generic permission hook ----
type PermStatus = 'undetermined' | 'granted' | 'denied';

interface PermissionOptions {
  request: () => Promise<{ status: string }>;
  check: () => Promise<{ status: string }>;
  featureName: string;
}

export function usePermission({ request, check, featureName }: PermissionOptions) {
  const [status, setStatus] = React.useState<PermStatus>('undetermined');

  useEffect(() => {
    check().then(result => setStatus(result.status as PermStatus));
  }, []);

  async function requestPermission(): Promise<boolean> {
    const result = await request();

    if (result.status === 'granted') {
      setStatus('granted');
      return true;
    }

    setStatus('denied');

    if (result.status === 'denied') {
      // Platform may have shown "Don't ask again" — must send user to Settings
      Alert.alert(
        `${featureName} Permission Required`,
        `Please enable ${featureName} access in your device settings for this feature to work.`,
        [
          { text: 'Cancel', style: 'cancel' },
          { text: 'Open Settings', onPress: () => Linking.openSettings() },
        ]
      );
    }

    return false;
  }

  return { status, requestPermission, isGranted: status === 'granted' };
}

// ---- Specialized hooks using the generic pattern ----
export function useCameraPermission() {
  return usePermission({
    request: Camera.requestCameraPermissionsAsync,
    check: Camera.getCameraPermissionsAsync,
    featureName: 'Camera',
  });
}

export function useLocationPermission() {
  return usePermission({
    request: Location.requestForegroundPermissionsAsync,
    check: Location.getForegroundPermissionsAsync,
    featureName: 'Location',
  });
}

// ---- Best practice: request in context, not at startup ----
function LocationButton() {
  const { isGranted, requestPermission } = useLocationPermission();

  async function handlePress() {
    if (isGranted) {
      showUserLocation(); // go straight to feature
    } else {
      const granted = await requestPermission(); // only asks when user taps button
      if (granted) showUserLocation();
    }
  }

  return (
    <Pressable onPress={handlePress} accessibilityRole="button" accessibilityLabel="Show my location">
      <Text>📍 Show my location</Text>
    </Pressable>
  );
}

function showUserLocation() {}

import { PermissionsAndroid, Platform } from 'react-native';

// For React Native CLI (non-Expo), Android permissions need explicit request
async function requestAndroidCameraPermission() {
  if (Platform.OS !== 'android') return true;

  const granted = await PermissionsAndroid.request(
    PermissionsAndroid.PERMISSIONS.CAMERA,
    {
      title: 'Camera Permission',
      message: 'This app needs camera access to scan barcodes',
      buttonPositive: 'Allow',
      buttonNegative: 'Deny',
    }
  );

  return granted === PermissionsAndroid.RESULTS.GRANTED;
}

// Must declare in AndroidManifest.xml:
// <uses-permission android:name="android.permission.CAMERA" />
// <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />