Navigator.js

// @flow
import React from 'react';
import { BackHandler } from 'react-native';
import { connect } from 'react-redux';
import { addNavigationHelpers, NavigationActions, StackNavigator } from 'react-navigation';
import type { NavigationState } from 'react-navigation/src/TypeDefinition';

import HomeScreen from './src/containers/Home';
import TimeChangeScreen from './src/containers/TimeChange';

export const Navigator = StackNavigator({
  Home: { screen: HomeScreen },
  TimeChange: { screen: TimeChangeScreen },
});

type Props = {
  nav: NavigationState,
  dispatch: Function,
};

class NavigatorWithState extends React.Component<Props> {
  componentDidMount() {
    BackHandler.addEventListener('hardwareBackPress', this.onBack);
  }

  componentWillUnmount() {
    BackHandler.removeEventListener('hardwareBackPress', this.onBack);
  }

  onBack = () => {
    const backAction = NavigationActions.back();
    const nav = Navigator.router.getStateForAction(backAction, this.props.nav);
    if (nav && nav !== this.props.nav) {
      this.props.dispatch(backAction);
      return true;
    }
    return false;
  };

  render() {
    return (
      <Navigator
        navigation={addNavigationHelpers({
          dispatch: this.props.dispatch,
          state: this.props.nav,
        })}
      />
    );
  }
}

const mapStateToProps = state => ({ nav: state.nav });

export default connect(mapStateToProps)(NavigatorWithState);