App.tsx

import React from 'react';
import { StyleSheet, Text, View, Button } from 'react-native';
import * as Notifications from 'expo-notifications';

Notifications.setNotificationHandler({
  handleSuccess: notificationIdentifier => {
    // dismiss every notification immediately after it is presented
    Notifications.dismissNotificationAsync(notificationIdentifier);
  },
  handleNotification: async () => ({
    shouldShowAlert: true,
    shouldPlaySound: true,
  }),
});

const NOTIFICATION_IDENTIFIER = 'whatever';

export default function App() {
  React.useEffect(() => {
    Notifications.requestPermissionsAsync({
      ios: {
        allowAlert: true,
        allowAnnouncements: true,
        allowSound: true,
      }
    });
  }, []);
  const showNotification = React.useCallback(() => {
    Notifications.scheduleNotificationAsync({
      identifier: NOTIFICATION_IDENTIFIER,
      content: {
        title: 'Hello there!',
        body: 'Here is the body.',
      },
      trigger: null,
    })
  }, []);
  const scheduleNotification = React.useCallback(() => {
    Notifications.scheduleNotificationAsync({
      identifier: NOTIFICATION_IDENTIFIER,
      content: {
        title: 'Hello there!',
        body: 'Here is the body.',
      },
      trigger: { seconds: 5 },
    })
  }, []);
  const dismissNotification = React.useCallback(() => {
    Notifications.dismissNotificationAsync(NOTIFICATION_IDENTIFIER);
  }, []);
  return (
    <View style={styles.container}>
      <Text>First, show the notification immediately, notice it will not stay in the Notification Center.</Text>
      <Button onPress={showNotification} title="Show push notification immediately" />
      <Text>Then, schedule the notification and background the app. Notice the notification stays in the Notification Center.</Text>
      <Button onPress={scheduleNotification} title="Show push notification in 5 seconds" />
      <Text>Dismiss the notification. It should be removed from the Notification Center.</Text>
      <Button onPress={dismissNotification} title="Dismiss the notification" />
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
    paddingHorizontal: 20,
  },
});