rnarch_nav_reducer_index

let initialState = {
  index: 0,
  routes: [
    {
      key: "initialLogin",
      routeName: <initial_screen_name>
    }
  ]
};

const navigationReducer = (state, action) => {
  const nextState = ApplicationNavigator.router.getStateForAction(
    action,
    state
  );

  return nextState || state;
};

export default navigationReducer;