app.navigation.js

import React from 'react';
import {createDrawerNavigator, createStackNavigator} from "react-navigation";
import Icon from 'react-native-vector-icons/FontAwesome';

import LoginScreen from '../screens/login.screen';
import RegisterScreen from '../screens/register.screen';

const headerIcon = (navigation, icon) => <Icon
    name={icon}
    style={{marginLeft: 20}}
    size={20}
    color="white"
    onPress={() => navigation.openDrawer()}
/>;

const navigationOptions = {
    navigationOptions: {
        headerStyle: {
            backgroundColor: 'rgba(200, 38, 74, 1)',
        },
        headerTitleStyle: {
            textAlign: 'center',
            alignSelf: 'center',
            fontSize: 20,
            color: '#fff',
            fontWeight: 'bold'
        }
    },
};

const loginScreenStack = createStackNavigator(
    {
        LoginScreen: {
            screen: LoginScreen,
            navigationOptions: ({navigation}) => ({
                title: 'Acceso',
                headerLeft: headerIcon(navigation, 'bars')
            })
        }
    },
    navigationOptions
);

const registerScreenStack = createStackNavigator(
    {
        RegisterScreen: {
            screen: RegisterScreen,
            navigationOptions: ({ navigation }) => ({
                title: 'Registro',
                headerLeft: headerIcon(navigation, 'bars')
            })
        }
    },
    navigationOptions
);

export default createDrawerNavigator(
    {
        Login: {
            screen: loginScreenStack,
            navigationOptions: ({ navigation }) => ({
                drawerLabel: 'Iniciar sesión',
                drawerIcon: ({tintColor}) => (<Icon name="sign-in" size={30} style={{color: tintColor}} />),
            })
        },
        Register: {
            screen: registerScreenStack,
            navigationOptions: ({ navigation }) => ({
                drawerLabel: 'Registrarme',
                drawerIcon: ({tintColor}) => (<Icon name="user" size={30} style={{color: tintColor}} />),
            })
        },
    },
    {
        initialRouteName: 'Login',
    }
)