Permissions

Overview

Modern mobile apps require explicit user permission to access sensitive features like camera, location, and notifications. This guide shows you how to properly request and handle permissions across platforms.

Permission Types

Common permissions in Expo apps:

Camera: Take photos and videos
Microphone: Record audio
Location: Access device location
Notifications: Send push notifications
Photos/Media Library: Access saved photos
Contacts: Access user contacts
Calendar: Access calendar events
Reminders: Access iOS reminders

Installation

Most Expo SDK packages include their own permission methods:

npx expo install expo-camera expo-location expo-notifications expo-media-library

Requesting Permissions

Basic pattern

All Expo permission APIs follow a similar pattern:

import * as Camera from 'expo-camera';

async function requestCameraPermission() {
  // Check current status
  const { status: existingStatus } = await Camera.getCameraPermissionsAsync();
  
  let finalStatus = existingStatus;
  
  // Request if not already granted
  if (existingStatus !== 'granted') {
    const { status } = await Camera.requestCameraPermissionsAsync();
    finalStatus = status;
  }
  
  // Handle the result
  if (finalStatus !== 'granted') {
    alert('Camera permission is required to take photos');
    return false;
  }
  
  return true;
}

Permission hook

Create a reusable hook for any permission:

hooks/usePermission.ts

import { useState, useEffect } from 'react';
import { PermissionResponse } from 'expo-modules-core';

type PermissionHook = {
  getAsync: () => Promise<PermissionResponse>;
  requestAsync: () => Promise<PermissionResponse>;
};

export function usePermission(permission: PermissionHook) {
  const [status, setStatus] = useState<PermissionResponse | null>(null);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    (async () => {
      const result = await permission.getAsync();
      setStatus(result);
      setLoading(false);
    })();
  }, []);

  const request = async () => {
    setLoading(true);
    const result = await permission.requestAsync();
    setStatus(result);
    setLoading(false);
    return result;
  };

  return {
    status: status?.status,
    granted: status?.status === 'granted',
    canAskAgain: status?.canAskAgain,
    loading,
    request,
  };
}

Usage:

components/CameraButton.tsx

import * as Camera from 'expo-camera';
import { usePermission } from '../hooks/usePermission';

export function CameraButton() {
  const camera = usePermission(Camera.useCameraPermissions());

  const handlePress = async () => {
    if (!camera.granted) {
      const result = await camera.request();
      if (!result.granted) {
        alert('Camera permission is required');
        return;
      }
    }
    
    // Open camera
    openCamera();
  };

  return (
    <Button 
      onPress={handlePress}
      title={camera.granted ? 'Take Photo' : 'Allow Camera Access'}
    />
  );
}

Common Permissions

Camera
Location
Media Library
Notifications
Contacts

import * as Camera from 'expo-camera';

async function takePicture() {
  const { status } = await Camera.requestCameraPermissionsAsync();
  
  if (status !== 'granted') {
    alert('Sorry, we need camera permissions to take photos!');
    return;
  }
  
  // Use camera
  const result = await ImagePicker.launchCameraAsync({
    mediaTypes: ImagePicker.MediaTypeOptions.Images,
    quality: 1,
  });
}

import * as Location from 'expo-location';

async function getLocation() {
  // Request foreground permission
  const { status } = await Location.requestForegroundPermissionsAsync();
  
  if (status !== 'granted') {
    alert('Permission to access location was denied');
    return;
  }

  const location = await Location.getCurrentPositionAsync({});
  console.log(location);
}

// For background location (iOS/Android 10+)
async function requestBackgroundLocation() {
  const { status: foregroundStatus } = 
    await Location.requestForegroundPermissionsAsync();
  
  if (foregroundStatus === 'granted') {
    const { status: backgroundStatus } = 
      await Location.requestBackgroundPermissionsAsync();
    
    return backgroundStatus === 'granted';
  }
  
  return false;
}

import * as MediaLibrary from 'expo-media-library';

async function savePhoto(uri: string) {
  const { status } = await MediaLibrary.requestPermissionsAsync();
  
  if (status !== 'granted') {
    alert('Permission to access media library is required');
    return;
  }

  await MediaLibrary.saveToLibraryAsync(uri);
  alert('Photo saved!');
}

async function getPhotos() {
  const { status } = await MediaLibrary.requestPermissionsAsync();
  
  if (status === 'granted') {
    const { assets } = await MediaLibrary.getAssetsAsync({
      first: 20,
      mediaType: 'photo',
    });
    
    return assets;
  }
}

import * as Notifications from 'expo-notifications';

async function registerForPushNotifications() {
  const { status: existingStatus } = 
    await Notifications.getPermissionsAsync();
  
  let finalStatus = existingStatus;
  
  if (existingStatus !== 'granted') {
    const { status } = await Notifications.requestPermissionsAsync();
    finalStatus = status;
  }
  
  if (finalStatus !== 'granted') {
    alert('Failed to get push notification permissions');
    return;
  }
  
  const token = await Notifications.getExpoPushTokenAsync();
  return token.data;
}

import * as Contacts from 'expo-contacts';

async function getContacts() {
  const { status } = await Contacts.requestPermissionsAsync();
  
  if (status !== 'granted') {
    alert('Permission to access contacts was denied');
    return;
  }

  const { data } = await Contacts.getContactsAsync({
    fields: [Contacts.Fields.PhoneNumbers, Contacts.Fields.Emails],
  });
  
  return data;
}

Permission States

Understanding permission status

type PermissionStatus = 
  | 'undetermined'  // Not yet asked
  | 'denied'        // User denied
  | 'granted'       // User granted
  | 'restricted';   // OS restriction (iOS)

Handling different states

async function handlePermission() {
  const { status, canAskAgain } = await Location.getForegroundPermissionsAsync();

  switch (status) {
    case 'granted':
      // Permission granted, proceed
      return true;
      
    case 'undetermined':
      // First time, ask for permission
      const result = await Location.requestForegroundPermissionsAsync();
      return result.status === 'granted';
      
    case 'denied':
      if (canAskAgain) {
        // Can ask again
        const result = await Location.requestForegroundPermissionsAsync();
        return result.status === 'granted';
      } else {
        // User selected "Don't ask again", direct to settings
        Alert.alert(
          'Permission Required',
          'Please enable location access in Settings',
          [
            { text: 'Cancel', style: 'cancel' },
            { text: 'Open Settings', onPress: () => Linking.openSettings() },
          ]
        );
        return false;
      }
      
    case 'restricted':
      // OS restriction (parental controls, etc.)
      Alert.alert(
        'Access Restricted',
        'Location access is restricted on this device'
      );
      return false;
  }
}

Platform Differences

iOS
Android

iOS-specific considerations

Permission descriptions required:Add usage descriptions in app.json:

app.json

{
  "expo": {
    "ios": {
      "infoPlist": {
        "NSCameraUsageDescription": "This app uses the camera to take photos for your profile.",
        "NSMicrophoneUsageDescription": "This app uses the microphone to record videos.",
        "NSLocationWhenInUseUsageDescription": "This app uses your location to show nearby places.",
        "NSLocationAlwaysAndWhenInUseUsageDescription": "This app uses your location to track your runs.",
        "NSPhotoLibraryUsageDescription": "This app accesses your photos to let you share them.",
        "NSPhotoLibraryAddUsageDescription": "This app saves photos to your library.",
        "NSCalendarsUsageDescription": "This app needs access to your calendar.",
        "NSRemindersUsageDescription": "This app needs access to your reminders.",
        "NSContactsUsageDescription": "This app needs access to your contacts."
      }
    }
  }
}

Your app will crash if you request a permission without the corresponding usage description.

Permission timing:

iOS only allows asking twice
After second denial, must use Settings
“Don’t Allow” vs “Ask Next Time”

Location precision (iOS 14+):

const { status } = await Location.requestForegroundPermissionsAsync();

// Check if precise location is enabled
const accuracy = await Location.getProviderStatusAsync();
console.log(accuracy.locationServicesEnabled);

Android-specific considerations

Permission declarations:Add permissions in app.json:

app.json

{
  "expo": {
    "android": {
      "permissions": [
        "CAMERA",
        "RECORD_AUDIO",
        "ACCESS_FINE_LOCATION",
        "ACCESS_COARSE_LOCATION",
        "READ_EXTERNAL_STORAGE",
        "WRITE_EXTERNAL_STORAGE",
        "READ_CONTACTS",
        "READ_CALENDAR",
        "WRITE_CALENDAR"
      ]
    }
  }
}

Android 10+ scoped storage:

app.json

{
  "expo": {
    "android": {
      "requestLegacyExternalStorage": true
    }
  }
}

Android 11+ (API 30) background location:

// Must request foreground first
const { status: foreground } = 
  await Location.requestForegroundPermissionsAsync();

if (foreground === 'granted') {
  // Then request background
  const { status: background } = 
    await Location.requestBackgroundPermissionsAsync();
}

Notification channels (Android 8+):

if (Platform.OS === 'android') {
  await Notifications.setNotificationChannelAsync('default', {
    name: 'Default',
    importance: Notifications.AndroidImportance.MAX,
  });
}

Best Practices

1. Request permissions in context

// Bad: Request all permissions upfront
useEffect(() => {
  requestAllPermissions();
}, []);

// Good: Request when needed
function handleTakePhoto() {
  requestCameraPermission().then(granted => {
    if (granted) openCamera();
  });
}

2. Explain why you need permission

function PermissionPrompt() {
  return (
    <View>
      <Text>We need access to your camera to:</Text>
      <Text>• Take profile photos</Text>
      <Text>• Scan QR codes</Text>
      <Text>• Upload documents</Text>
      <Button onPress={requestPermission} title="Allow Camera Access" />
    </View>
  );
}

3. Handle all permission states

function LocationPermissionScreen() {
  const { status, request } = usePermission(Location.useForegroundPermissions());

  if (status === 'granted') {
    return <MapView />;
  }

  if (status === 'denied') {
    return (
      <View>
        <Text>Location access was denied</Text>
        <Button onPress={() => Linking.openSettings()} title="Open Settings" />
      </View>
    );
  }

  return (
    <View>
      <Text>We need your location to show nearby places</Text>
      <Button onPress={request} title="Allow Location Access" />
    </View>
  );
}

4. Graceful degradation

async function shareWithContacts() {
  const { status } = await Contacts.requestPermissionsAsync();
  
  if (status === 'granted') {
    // Show contact picker
    const contacts = await Contacts.getContactsAsync();
    return contacts;
  } else {
    // Fallback: manual phone number entry
    return showPhoneNumberInput();
  }
}

5. Check before requesting

async function ensurePermission() {
  // Check current status first
  const { status } = await Camera.getCameraPermissionsAsync();
  
  if (status === 'granted') {
    return true;
  }
  
  // Only request if needed
  const { status: newStatus } = await Camera.requestCameraPermissionsAsync();
  return newStatus === 'granted';
}

Debugging Permissions

Log permission status

async function debugPermissions() {
  const camera = await Camera.getCameraPermissionsAsync();
  const location = await Location.getForegroundPermissionsAsync();
  const notifications = await Notifications.getPermissionsAsync();
  
  console.log('Permissions:', {
    camera: camera.status,
    location: location.status,
    notifications: notifications.status,
  });
}

Reset permissions (development)

iOS
Android

# Simulator
xcrun simctl privacy booted reset all com.company.myapp

# Or: Settings > General > Reset > Reset Location & Privacy

# Uninstall and reinstall
adb uninstall com.company.myapp

# Or: Settings > Apps > MyApp > Permissions > Reset

Troubleshooting

App crashes when requesting permission

iOS: Ensure you’ve added the usage description to app.json:

"NSCameraUsageDescription": "This app needs camera access"

Rebuild after adding: npx expo prebuild --clean

Permission denied without showing prompt

User previously denied with “Don’t ask again” (Android)
User denied twice already (iOS)
Direct user to Settings with Linking.openSettings()

Permission granted but feature not working

Check for additional permissions (e.g., location + background location)
Verify device settings (Location Services enabled)
Check for OS restrictions (parental controls)

Permission prompt not appearing

Verify you’re calling requestAsync() not just getAsync()
Check permission isn’t already granted or permanently denied
Ensure you’ve declared the permission in app.json (Android)

Always rebuild your app after modifying permissions in app.json: npx expo prebuild --clean

Permission Reference

Quick reference for common permission methods:

Feature	Package	Get Permission	Request Permission
Camera	expo-camera	`getCameraPermissionsAsync()`	`requestCameraPermissionsAsync()`
Location	expo-location	`getForegroundPermissionsAsync()`	`requestForegroundPermissionsAsync()`
Media Library	expo-media-library	`getPermissionsAsync()`	`requestPermissionsAsync()`
Notifications	expo-notifications	`getPermissionsAsync()`	`requestPermissionsAsync()`
Audio	expo-av	`getPermissionsAsync()`	`requestPermissionsAsync()`
Contacts	expo-contacts	`getPermissionsAsync()`	`requestPermissionsAsync()`
Calendar	expo-calendar	`getCalendarPermissionsAsync()`	`requestCalendarPermissionsAsync()`

Platform Features

Advanced Topics

Optimization

Permissions

Overview

Permission Types

Installation

Requesting Permissions

Basic pattern

Permission hook

Common Permissions

Permission States

Understanding permission status

Handling different states

Platform Differences

iOS-specific considerations

Android-specific considerations

Best Practices

1. Request permissions in context

2. Explain why you need permission

3. Handle all permission states

4. Graceful degradation

5. Check before requesting

Debugging Permissions

Log permission status

Reset permissions (development)

Troubleshooting

Permission Reference

Platform Features

Advanced Topics

Optimization

​Overview

​Permission Types

​Installation

​Requesting Permissions

​Basic pattern

​Permission hook

​Common Permissions

​Permission States

​Understanding permission status

​Handling different states

​Platform Differences

​iOS-specific considerations

​Android-specific considerations

​Best Practices

​1. Request permissions in context

​2. Explain why you need permission

​3. Handle all permission states

​4. Graceful degradation

​5. Check before requesting

​Debugging Permissions

​Log permission status

​Reset permissions (development)

​Troubleshooting

​Permission Reference

​Related Resources

Overview

Permission Types

Installation

Requesting Permissions

Basic pattern

Permission hook

Common Permissions

Permission States

Understanding permission status

Handling different states

Platform Differences

iOS-specific considerations

Android-specific considerations

Best Practices

1. Request permissions in context

2. Explain why you need permission

3. Handle all permission states

4. Graceful degradation

5. Check before requesting

Debugging Permissions

Log permission status

Reset permissions (development)

Troubleshooting

Permission Reference

Related Resources