Here we are passing stateForLoggedIn if the user is logged in or stateForLoggedOut if the user is logged out.

conditionalStateToNavigator.js

// our navigationReducer which will feed AppNavigator with navigation state ---> https://gist.github.com/shubhnik/9f7bafd3145e66434705cd1e995d1356
// Don't forget to check the complete code here ---> https://github.com/shubhnik/redux-react-navigation/tree/authFlow
const AppNavigator = StackNavigator({
  login: {
    screen: Login
  },
  screen1: {
    screen: Screen1
  },
  screen2: {
    screen: Screen2
  }
});

class AppNavigation extends Component {
  render() {
    const { navigationState, dispatch, isLoggedIn } = this.props;
    const state = isLoggedIn
      ? navigationState.stateForLoggedIn
      : navigationState.stateForLoggedOut;
    return (
      <NavigationStack
        navigation={addNavigationHelpers({ dispatch, state})}
      />
    );
  }
}

const mapStateToProps = state => {
  return {
    isLoggedIn: state.LoginReducer.isLoggedIn,
    navigationState: state.NavigationReducer
  };
};

export default connect(mapStateToProps)(AppNavigation);