main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

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

class MyController with ChangeNotifier {
  MyController();

  bool _privacyPolicy = false;
  bool get privacyPolicy => _privacyPolicy;
  set privacyPolicy(bool privacyPolicy) {
    if (_privacyPolicy != privacyPolicy) {
      _privacyPolicy = privacyPolicy;
      notifyListeners();
    }
  }

  bool _tos = false;
  bool get tos => _tos;
  set tos(bool tos) {
    if (_tos != tos) {
      _tos = tos;
      notifyListeners();
    }
  }

  @override
  void dispose() {
    // if you need cleanup
    super.dispose();
  }
}

class MyScreen extends StatefulWidget {
  const MyScreen({super.key});

  @override
  State<MyScreen> createState() => _MyScreenState();
}

class _MyScreenState extends State<MyScreen>
    with SingleTickerProviderStateMixin {
  late final TabController _tabController;
  late final MyController _myController;

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

  @override
  void dispose() {
    _tabController.dispose();
    _myController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('My Screen'),
        bottom: TabBar(
          controller: _tabController,
          tabs: const [
            Tab(text: 'A'),
            Tab(text: 'B'),
          ],
        ),
      ),
      body: TabBarView(
        controller: _tabController,
        children: [
          A(myController: _myController),
          B(myController: _myController),
        ],
      ),
    );
  }
}

class A extends StatelessWidget {
  const A({
    super.key,
    required this.myController,
  });

  final MyController myController;

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: myController,
      builder: (context, child) => Column(
        children: [
          SwitchListTile.adaptive(
            title: const Text('Privacy Policy'),
            value: myController.privacyPolicy,
            onChanged: (value) {
              myController.privacyPolicy = value;
            },
          ),
          SwitchListTile.adaptive(
            title: const Text('Terms of Service'),
            value: myController.tos,
            onChanged: (value) {
              myController.tos = value;
            },
          ),
        ],
      ),
    );
  }
}

class B extends StatelessWidget {
  const B({
    super.key,
    required this.myController,
  });

  final MyController myController;

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: myController,
      builder: (context, child) => Column(
        children: [
          ListTile(
            title: const Text('Privacy Policy'),
            subtitle: Text(myController.privacyPolicy.toString()),
          ),
          ListTile(
            title: const Text('Terms of Service'),
            subtitle: Text(myController.tos.toString()),
          ),
        ],
      ),
    );
  }
}