React Native & Firebase: App.js

App.js

import React, { Component, Fragment } from 'react';
import firebase from 'react-native-firebase';

class App extends Component<Props> {
...
  getToken = async () => {
    let fcmToken = await AsyncStorage.getItem('fcmToken');
    if (!fcmToken) {
      fcmToken = await firebase.messaging().getToken();
      if (fcmToken) {
        await AsyncStorage.setItem('fcmToken', fcmToken);
      }
    }
  };

  checkPermission = async () => {
    const enabled = await firebase.messaging().hasPermission();
    if (enabled) {
      this.getToken();
    } else {
      this.requestPermission();
    }
  };

  requestPermission = async () => {
    try {
      await firebase.messaging().requestPermission();
      this.getToken();
    } catch (error) {
      console.log('permission rejected');
    }
  };

  createNotificationListeners = () => {
    this.onUnsubscribeNotificaitonListener = firebase
      .notifications()
      .onNotification(notification => {
        firebase.notifications().displayNotification(notification);
      });
  };

  removeNotificationListeners = () => {
    this.onUnsubscribeNotificaitonListener();
  };

  componentDidMount() {
    // Build a channel
    const channel = new firebase.notifications.Android.Channel('test-channel', 'Test Channel', firebase.notifications.Android.Importance.Max)
    .setDescription('My apps test channel');

    // Create the channel
    firebase.notifications().android.createChannel(channel);
    this.checkPermission();
    this.createNotificationListeners();
  }

  componentWillUnmount() {
    this.removeNotificationListeners();
  }
  
  ...
  }