App.js

import { NavigationContainer } from '@react-navigation/native';
import { createStackNavigator } from '@react-navigation/stack';
import React, { useState, useEffect } from 'react';
import { Platform, StatusBar, StyleSheet, View, Vibration } from 'react-native';
import { Notifications } from 'expo';
import * as Permissions from 'expo-permissions';
import Constants from 'expo-constants';

import useCachedResources from './hooks/useCachedResources';
import BottomTabNavigator from './navigation/BottomTabNavigator';
import LinkingConfiguration from './navigation/LinkingConfiguration';
import PrioritySelectionScreen from './screens/PrioritySelectionScreen'
import PublishEventScreen from './screens/PublishEventScreen';
import FriendScreen from './screens/FriendScreen';

const Stack = createStackNavigator();

export default function App(props) {
  const [expoPushToken, setExpoPushToken] = useState('');
  const [notification, setNotification] = useState({});

  const isLoadingComplete = useCachedResources();

  async function registerForPushNotificationsAsync () {
    if (Constants.isDevice) {
      const { status: existingStatus } = await Permissions.getAsync(Permissions.NOTIFICATIONS);
      let finalStatus = existingStatus;
      if (existingStatus !== 'granted') {
        const { status } = await Permissions.askAsync(Permissions.NOTIFICATIONS);
        finalStatus = status;
      }
      if (finalStatus !== 'granted') {
        console.log('Failed to get push token for push notification!');
        return;
      }
      token = await Notifications.getExpoPushTokenAsync();
      console.log(token);
      setExpoPushToken(token);
    } else {
      console.log('Must use physical device for Push Notifications');
    }

    if (Platform.OS === 'android') {
      Notifications.createChannelAndroidAsync('default', {
        name: 'default',
        sound: true,
        priority: 'max',
        vibrate: [0, 250, 250, 250],
      });
    }
  }

  useEffect(() => {
    registerForPushNotificationsAsync();
    Notifications.addListener(_handleNotification);
  }, []);

  function _handleNotification(notification) {
    Vibration.vibrate();
    console.log(notification);
    setNotification(notification);
  }

  if (!isLoadingComplete) {
    return null;
  } else {
    return (
      <View style={styles.container}>
        {Platform.OS === 'ios' && <StatusBar barStyle="dark-content" />}
        <NavigationContainer linking={LinkingConfiguration}>
          <Stack.Navigator>
            <Stack.Screen name="Root" component={BottomTabNavigator} />
            <Stack.Screen name="PrioritySelectionScreen" component={PrioritySelectionScreen} />
            <Stack.Screen name="PublishEventScreen" component={PublishEventScreen} />
            <Stack.Screen name="FriendScreen" component={FriendScreen} />
          </Stack.Navigator>
        </NavigationContainer>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
  },
});