The selected view is not changed when drag gestures change the view

I use the following code to create a PageView:

class HomeScreen extends StatefulWidget {
  const HomeScreen({Key? key}) : super(key: key);

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  int _selectedIndex = 0;
  PageController pageController = PageController();

  void onTapped(int index) {
    setState(() {
      _selectedIndex = index;

      pageController.animateToPage(index,
          duration: const Duration(milliseconds: 300),
          curve: Curves.ease);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: null,
      body: PageView(
        controller: pageController,
        //We can add widets to each tab page
        children: [
          Container(
            color: Colors.red,
          ),
          Container(
            color: Colors.blue,
          ),
          Container(
            color: Colors.green,
          )
        ],
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: const <BottomNavigationBarItem>[
          BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Home'),
          BottomNavigationBarItem(icon: Icon(Icons.paste), label: 'Report'),
          BottomNavigationBarItem(icon: Icon(Icons.settings), label: 'Settings')
        ],
        currentIndex: _selectedIndex,
        selectedItemColor: Colors.white,
        unselectedItemColor: Colors.grey,
        onTap: onTapped,
      ),
    );
  }
}

I can navigate through views by pressing the view icons below but when I use the drag gesture to change the view, the selected view is not changed. How can I fix it?

>Solution :

You can include a listener on PageController to update the navbar item.

  late PageController pageController = PageController()
    ..addListener(() {
      setState(() {
        _selectedIndex = pageController.page?.toInt() ?? 0;
      });
    });

Or onPageChanged

onPageChanged: (value) {
  _selectedIndex = value;
  setState(() {});
},