react-native-firebase/packages/template/project/App.js

/**
 * Sample React Native App with Firebase
 * https://github.com/invertase/react-native-firebase
 *
 * @format
 * @flow
 */

import React, { Component } from 'react';
import { Platform, StyleSheet, Text, View } from 'react-native';

import firebase from '@react-native-firebase/app';

// TODO(you): import any additional firebase services that you require for your app, e.g for auth:
//    1) install the npm package: `yarn add @react-native-firebase/auth@alpha` - you do not need to
//       run linking commands - this happens automatically at build time now
//    2) rebuild your app via `yarn run run:android` or `yarn run run:ios`
//    3) import the package here in your JavaScript code: `import '@react-native-firebase/auth';`
//    4) The Firebase Auth service is now available to use here: `firebase.auth().currentUser`

const instructions = Platform.select({
  ios: 'Press Cmd+R to reload,\nCmd+D or shake for dev menu',
  android: 'Double tap R on your keyboard to reload,\nShake or press menu button for dev menu',
});

const firebaseCredentials = Platform.select({
  ios: 'https://invertase.link/firebase-ios',
  android: 'https://invertase.link/firebase-android',
});

type Props = {};

export default class App extends Component<Props> {
  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>Welcome to React Native + Firebase!</Text>
        <Text style={styles.instructions}>To get started, edit App.js</Text>
        <Text style={styles.instructions}>{instructions}</Text>
        {!firebase.apps.length && (
          <Text style={styles.instructions}>
            {`\nYou currently have no Firebase apps registered, this most likely means you've not downloaded your project credentials. Visit the link below to learn more. \n\n ${firebaseCredentials}`}
          </Text>
        )}
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,
  },
});