text: import { createSwitchNavigator, createBottomTabNavigator, createStackNavigator, createAppContainer } from "react-navigation";
  
  // import yours screens
  import LaunchScreen from '../Containers/Launch/LaunchScreen'
  
  import Tutorial from '../Containers/Tutorial/TutorailScreen'
  import LoginScreen from '../Containers/Login/LoginScreen'
  import SubscribeScreen from '../Containers/Subscribe/SubscribeScreen'
  
  import Tab1 from '../Containers/Tab1/Tab1'
  import Tab2 from '../Containers/Tab2/Tab2'
  import Tab3 from '../Containers/Tab3/Tab3'
  
  import Details from '../Containers/Details/DetailsScreen'
  
  // style the header with a stylish violet
  const headerStyleViolet = ({ navigation }) => ({
    headerTitleStyle: { color: 'white' },
    headerStyle: {
      backgroundColor: 'violet',
    },
    headerTintColor: 'white',
  })
  
  // style the header with a christmas red
  const headerStyleRed = ({ navigation }) => ({
    headerTitleStyle: { color: 'white' },
    headerStyle: { backgroundColor: 'red' },
    headerTintColor: 'white'
  })
  
  // style the header with crazy colors
  const headerStyleCrazy = ({ navigation }) => ({
    headerTitleStyle: { color: '#e45f92' },
    headerStyle: { backgroundColor: '#e3f134' },
    headerTintColor: '#12ff32'
  })
  
  
  const AppNavigator = createSwitchNavigator({
    Launch: {
      screen: LaunchScreen
    },
    Auth: {
      screen: createStackNavigator({
        Tutorial: Tutorial,
        Login: {
          screen: LoginScreen,
          navigationOptions: headerStyleViolet
        },
        Subscribe: {
          screen: SubscribeScreen,
          navigationOptions: headerStyleRed
        }
      },
      {
        initialRouteName: 'Tutorial',
        headerStyle: {
          backgroundColor: 'violet'
        },
        headerLayoutPreset: 'center' // to center the title text (Android) default is 'left'
      })
    },
    App: {
      screen: createBottomTabNavigator({
        Tab1: Tab1,
        Tab2: Tab2,
        Tab3: createStackNavigator({
          Tab3: Tab3,
          Details: {
            screen: Details,
            navigationOptions: headerStyleCrazy
          }
        })
      },{
        tabBarOptions: {
          activeTintColor: 'tomato',
          inactiveTintColor: 'gray',
        },
      })
    }
  });
  
  export default createAppContainer(AppNavigator);