App.js

import React from "react";
import { StyleSheet, Text, View } from "react-native";
import WelcomeScreen from "./screens/WelcomeScreen";
import { AppTabNavigator } from "./components/AppTabNavigator";
import { createAppContainer, createSwitchNavigator } from "react-navigation";
import { AppDrawerNavigator } from "./components/AppDrawerNavigator";

export default function App() {
  return <AppContainer />;
}

const SwitchNavigator = createSwitchNavigator({
  WelcomeScreen: { screen: WelcomeScreen },
  Drawer: { screen: AppDrawerNavigator },
  BottomTab: {screen: AppTabNavigator}
});

const AppContainer = createAppContainer(SwitchNavigator);

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: "#fff",
    alignItems: "center",
    justifyContent: "center",
  },
});