code: public void onCreate(Activity activity, Bundle savedInstanceState) {
      this.activity = activity;
      container = (ScreenContainer) activity.findViewById(R.id.magellan_container);
      checkState(container != null, "There must be a ScreenContainer whose id is R.id.magellan_container in the view hierarchy");
      for (Screen screen : backStack) {
        screen.restore(savedInstanceState);
        screen.onRestore(savedInstanceState);
      }
      showCurrentScreen(FORWARD);
    }
docs: Initializes the Navigator with Activity instance and Bundle for saved instance state.
  
  Call this method from {@link Activity#onCreate(Bundle) onCreate} of the Activity associated with this Navigator.
  
  @param activity  Activity associated with application
  @param savedInstanceState  state to restore from previously destroyed activity
  @throws IllegalStateException when no {@link ScreenContainer} view present in hierarchy with view id of container