App.js

import React from 'react';
import { Platform, StatusBar, StyleSheet, View } from 'react-native';
import { AppLoading, Asset, Font, Icon } from 'expo';
import AppNavigator from './navigation/AppNavigator';
import { FIREBASE_API_KEY, AUTH_DOMAIN, DATABASE_URL, FIREBASE_PROJECT_ID,STORAGE_BUCKET, MESSAGE_ID } from 'react-native-dotenv';

import * as firebase from 'firebase';
const config = {
  apiKey: FIREBASE_API_KEY,
  authDomain: AUTH_DOMAIN,
  databaseURL: DATABASE_URL,
  projectId: FIREBASE_PROJECT_ID,
  storageBucket: STORAGE_BUCKET,
  messagingSenderId: MESSAGE_ID
};
firebase.initializeApp(config);

import {YellowBox} from 'react-native';
YellowBox.ignoreWarnings(['Setting a timer']);

export default class App extends React.Component {
  state = {
    isLoadingComplete: false,
  };

  render() {
    if (!this.state.isLoadingComplete && !this.props.skipLoadingScreen) {
      return (
        <AppLoading
          startAsync={this._loadResourcesAsync}
          onError={this._handleLoadingError}
          onFinish={this._handleFinishLoading}
        />
      );
    } else {
      return (
        <View style={styles.container}>
          {Platform.OS === 'ios' && <StatusBar barStyle="default" />}
          <AppNavigator />
        </View>
      );
    }
  }

  _loadResourcesAsync = async () => {
    return Promise.all([
      Asset.loadAsync([
        require('./assets/images/robot-dev.png'),
        require('./assets/images/robot-prod.png'),
      ]),
      Font.loadAsync({
        // This is the font that we are using for our tab bar
        ...Icon.Ionicons.font,

        'nunito': require('./assets/fonts/Nunito-Regular.ttf'),
        'nunito-bold': require('./assets/fonts/Nunito-Bold.ttf'),
      }),
    ]);
  };

  _handleLoadingError = error => {
    // In this case, you might want to report the error to your error
    // reporting service, for example Sentry
    console.warn(error);
  };

  _handleFinishLoading = () => {
    this.setState({ isLoadingComplete: true });
  };
}

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