src/index.js

import React, { Component } from "react";
import Root from "./routes/index";
import NavigationService from "./actions/utils/helpers";
import { store } from "./store";
import { setCurrentRouteName } from "./actions/navigation";

class App extends Component {
  _getCurrentRouteName = navState => {
    if (navState.hasOwnProperty("index")) {
      this._getCurrentRouteName(navState.routes[navState.index]);
    } else {
      store.dispatch(setCurrentRouteName(navState.routeName));
    }
    return;
  };

  render() {
    return (
      <Root
        onNavigationStateChange={(prevState, newState) => {
          this._getCurrentRouteName(newState);
        }}
        ref={navigatorRef => {
          NavigationService.setTopLevelNavigator(navigatorRef);
        }}
      />
    );
  }
}

export default App;