Hide Appbar on Scroll Flutter?

If I understood you correctly, following code should make the app bar hide on scroll while TabBar remains visible:

Null safe code:

class _SomePageState extends State<SomePage> with SingleTickerProviderStateMixin {
  late final TabController _tabController;

  @override
  void initState() {
    super.initState();
    _tabController = TabController(length: 2, vsync: this);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: NestedScrollView(
        headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
          return <Widget>[
            SliverAppBar(
              title: Text('Weight Tracker'),
              pinned: true,
              floating: true,
              forceElevated: innerBoxIsScrolled,
              bottom: TabBar(
                tabs: <Tab>[
                  Tab(text: 'STATISTICS'),
                  Tab(text: 'HISTORY'),
                ],
                controller: _tabController,
              ),
            ),
          ];
        },
        body: TabBarView(
          controller: _tabController,
          children: <Widget>[
            StatisticsPage(),
            HistoryPage(),
          ],
        ),
      ),
    );
  }
}

Example coming from this post.