【Flutter】スクロールした際フッターメニュータブを非表示にする方法

import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  ScrollController _controller = ScrollController();
  bool _isVisible = true;

  @override
  void initState() {
    super.initState();
    _controller.addListener(() {
      if (_controller.position.userScrollDirection == ScrollDirection.reverse) {
        if (_isVisible == true) {
          setState(() {
            _isVisible = false;
          });
        }
      } else {
        if (_controller.position.userScrollDirection == ScrollDirection.forward) {
          if (_isVisible == false) {
            setState(() {
              _isVisible = true;
            });
          }
        }
      }
    });
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('スクロールでフッター非表示'),
      ),
      body: ListView.builder(
        controller: _controller,
        itemCount: 100,
        itemBuilder: (context, index) => ListTile(
          title: Text('アイテム $index'),
        ),
      ),
      bottomNavigationBar: _isVisible
          ? BottomNavigationBar(
              items: const <BottomNavigationBarItem>[
                BottomNavigationBarItem(
                  icon: Icon(Icons.home),
                  label: 'ホーム',
                ),
                BottomNavigationBarItem(
                  icon: Icon(Icons.search),
                  label: '検索',
                ),
              ],
            )
          : null,
    );
  }
}