Theme with riverpod - StateNotifier

main.dart

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


class ThemeNotifier extends StateNotifier<ThemeData> {
  ThemeNotifier() : super(ThemeData.light());

  bool isLight() {
    return state == ThemeData.light();
  }
  
  void toggleTheme() {
    state = isLight() ? ThemeData.dark() : ThemeData.light();
  }
}

final themeDataProvider = StateNotifierProvider<ThemeNotifier, ThemeData>((ref) {
  return ThemeNotifier();
});


void main() {
  runApp(ProviderScope(child: MyApp()));
}

class MyApp extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final themeData = ref.watch(themeDataProvider);
    return MaterialApp(
      title: 'Flutter Theme Switcher',
      theme: themeData,
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final theme = ref.watch(themeDataProvider);
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Theme Switcher'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'Current Theme: ${theme == ThemeData.light() ? "Light" : "Dark"}',
            ),
            Switch(
              value: theme == ThemeData.dark(),
              onChanged: (bool value) {
                ref.read(themeDataProvider.notifier).toggleTheme();
              },
            ),
          ],
        ),
      ),
    );
  }
}