RootNavigation.js

import { Notifications } from 'expo';
import React from 'react';
import { StackNavigator } from 'react-navigation';
import { TouchableOpacity } from 'react-native';
import { Entypo } from '@expo/vector-icons';
import MainTabNavigator from './MainTabNavigator';
import registerForPushNotificationsAsync from '../api/registerForPushNotificationsAsync';
import HomeScreen from '../screens/HomeScreen';

const RootStackNavigator = StackNavigator(
  {
    HomeScreen: {
      screen: HomeScreen,
      navigationOptions: {
        tabBarVisible: false
      }
    },
    Main: {
      screen: MainTabNavigator,
    }
// other routes objects
  },
  {
    // initialRoute: 'HomeScreen',
    navigationOptions: ({ navigation }) => ({
      headerTitleStyle: {
        fontWeight: 'normal',
      },
      headerLeft:
      <TouchableOpacity
        onPress={() => {
          if(navigation.state.index === 0) {
            navigation.navigate('DrawerOpen');
          } else {
            navigation.navigate('DrawerClose');
          }
        }}
               style={{ padding: 10 }}>
          <Entypo name={navigation.state.index === 0 ? 'menu' : 'chevron-small-left'} size={32} color="#000"         >
      </TouchableOpacity>
    }),
  }
);

export default class RootNavigator extends React.Component {
  componentDidMount() {
    this._notificationSubscription = this._registerForPushNotifications();
  }

  componentWillUnmount() {
    this._notificationSubscription && this._notificationSubscription.remove();
  }

  render() {
    return <RootStackNavigator />;
  }

  _registerForPushNotifications() {
    // Send our push token over to our backend so we can receive notifications
    // You can comment the following line out if you want to stop receiving
    // a notification every time you open the app. Check out the source
    // for this function in api/registerForPushNotificationsAsync.js
    registerForPushNotificationsAsync();

    // Watch for incoming notifications
    this._notificationSubscription = Notifications.addListener(this._handleNotification);
  }

  _handleNotification = ({ origin, data }) => {
    console.log(`Push notification ${origin} with data: ${JSON.stringify(data)}`);
  };
}