export default function App() {
  useEffect(() => {
    const handleAppStateChange = (nextAppState: AppStateStatus) => {
      if (nextAppState === 'active') {
        // App has come to the foreground
        console.log('App is in foreground');
      } else if (nextAppState === 'background') {
        // App has gone to the background
        console.log('App is in background');
      } else if (nextAppState === 'inactive') {
        // App is in an intermediate state
        console.log('App is inactive');
      }
    };

    AppState.addEventListener('change', handleAppStateChange);

    return () => {
      AppState.removeEventListener('change', handleAppStateChange);
    };
  }, []);
	return ( /* Your component JSX */ );
};

import React, { useEffect } from 'react';
import { AppState, AppStateStatus } from 'react-native';

import { Stack } from 'expo-router';

export default function Layout() {
  return (
    <Stack
      screenOptions={{
        headerStyle: {
          backgroundColor: '#f4511e',
        },
        headerTintColor: '#fff',
        headerTitleStyle: {
          fontWeight: 'bold',
        },
      }}>
      {/* Optionally configure static options outside the route.*/}
      <Stack.Screen name="home" options={{}} />
    </Stack>
  );
}

export default function Home() {
  return (
    <View style={styles.container}>
      <Stack.Screen
        options={{
          title: 'My home',
          headerStyle: { backgroundColor: '#f4511e' },
          headerTintColor: '#fff',
          headerTitleStyle: {
            fontWeight: 'bold',
          },

          headerTitle: props => <LogoTitle {...props} />,
        }}
      />
      <Text>Home Screen</Text>
      <Link href={{ pathname: 'details', params: { name: 'Bacon' } }}>Go to Details</Link>
    </View>
  );
}

export default function Details() {
  const router = useRouter();
  const params = useLocalSearchParams();

  return (
    <View style={styles.container}>
      <Stack.Screen
        options={{
          title: params.name,
        }}
      />
      <Text onPress={() => { router.setParams({ name: 'Updated' }); }}>
        Update the title
      </Text>
    </View>
  );
}

expo install @react-native-async-storage/async-storage

import AsyncStorage from '@react-native-async-storage/async-storage';

export default function AsyncStorageExample  () {
  const [storedData, setStoredData] = useState('');
  const storeData = async () => {
    try {
      await AsyncStorage.setItem('@myStorageKey', 'Hello, AsyncStorage!');
      alert('Data stored successfully!');
    } catch (e) {
      alert('Failed to store data.');
    }
  };
  const retrieveData = async () => {
    try {
      const value = await AsyncStorage.getItem('@myStorageKey');
      if (value !== null) {
        setStoredData(value);
      } else {
        alert('No data found.');
      }
    } catch (e) {
      alert('Failed to retrieve data.');
    }
  };
};

return (
    <View style={{ 
    	flex: 1, 
        justifyContent: 'center', 
        alignItems: 'center' 
       }}>
      <Text>Stored Data: {storedData}</Text>
      <Button title="Store Data" onPress={storeData} />
      <Button title="Retrieve Data" onPress={retrieveData} />
    </View>
);

if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
        != PackageManager.PERMISSION_GRANTED) {
    // Permission is not granted, request it
    ActivityCompat.requestPermissions(this,
            new String[]{Manifest.permission.CAMERA},
            CAMERA_PERMISSION_REQUEST_CODE);
}

let locationManager = CLLocationManager()
locationManager.requestWhenInUseAuthorization()
AVCaptureDevice.requestAccess(for: .video) { (granted: Bool) in
    if granted {
        // Permission granted, proceed with using the camera
    } else {
        // Permission denied, handle accordingly
    }
}

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

async function requestCameraPermission() {
  if (Platform.OS === 'android') {
    try {
      const granted = await PermissionsAndroid.request(
        PermissionsAndroid.PERMISSIONS.CAMERA,
        {
          title: 'Camera Permission',
          message: 'App needs access to your camera.',
          buttonNeutral: 'Ask Me Later',
          buttonNegative: 'Cancel',
          buttonPositive: 'OK',
        }
      );
      if (granted === PermissionsAndroid.RESULTS.GRANTED) console.log('Camera permission granted');
      else  console.log('Camera permission denied');
    } catch (err) {
      console.warn(err);
    }
  } else {
    // iOS specific permission handling
    // Example using Expo Permissions module:
    // const { status } = await Permissions.askAsync(Permissions.CAMERA);
  }
}

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

async function checkLocationPermission() {
  if (Platform.OS === 'android') {
    try {
      const granted = await PermissionsAndroid.check(
        PermissionsAndroid.PERMISSIONS.ACCESS_FINE_LOCATION
      );
      if (granted) {
        console.log('Location permission granted');
      } else {
        console.log('Location permission denied');
      }
    } catch (err) {
      console.warn(err);
    }
  } else {
    // iOS specific permission handling
    // Example using Expo Permissions module:
    // const { status } = await Permissions.askAsync(Permissions.LOCATION);
  }
}