With this article, I added dark and light themes in the MaterialApp.
Now it's time to add a toggle switch in the app. I'll use riverpod. One of the famous framework people uses for state management. As expressed in the official document, It's more caching framework itself, but It's helpful to cache the global states.
Setup the riverpod
-
Add the riverpod package
flutter pub add flutter_riverpod
-
Wrap the MainApp with the ProviderScope
From:
void main() { runApp(const MyApp()); }
To:
void main() { runApp(const ProviderScope(child: MyApp())); }
Implement the theme toggle switch
-
Add the
themeModeProvider
final themeModeProvider = StateProvider<ThemeMode>((ref) { return ThemeMode.dark; });
-
Convert the
MyApp
asConsumerWidget
and watch the provider
class MyApp extends ConsumerWidget { const MyApp({super.key}); @override Widget build(BuildContext context, WidgetRef ref) { final themMode = ref.watch(themeModeProvider); return MaterialApp( title: 'Flutter Demo', theme: ThemeData( useMaterial3: true, colorScheme: lightColorScheme, textTheme: textTheme, ), darkTheme: ThemeData( useMaterial3: true, colorScheme: darkColorScheme, textTheme: textTheme, ), themeMode: themMode, // Apply them theme home: const MyHomePage(title: 'Flutter Demo Home Page'), ); } }
Every time the themeModeProvider changes, the widget rebuilds and assigns the new value to the
themeMode
final themMode = ref.watch(themeModeProvider);
-
Add the toggle button
Consumer(builder: (context, ref, child) { final theme = ref.watch(themeModeProvider); return IconButton( onPressed: () { ref.read(themeModeProvider.notifier).state = theme == ThemeMode.light ? ThemeMode.dark : ThemeMode.light; }, icon: Icon(theme == ThemeMode.dark ? Icons.light_mode : Icons.dark_mode)); })
The complete code can be found on github
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