App.js

import React from 'react';
import { AppRegistry, StyleSheet, Text, View, AsyncStorage } from 'react-native';
import { StackNavigator } from 'react-navigation';

import HomeScreen from './screens/HomeScreen';
import UserScreen from './screens/users/UserScreen';

export default class App extends React.Component {
  async getId()
  {
    return await AsyncStorage.getItem("id");
  }
  render() {
    if (this.getId() !== null && this.getId() !== "")
    {
      return (
        <HomeScreen></HomeScreen>
      );
    }
    else
    {
      return (
        <UserScreen></UserScreen>
      );
    }
  }
}