Flutter cross platform data persistence solution: shared_preferences with riverpod

main.dart

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

// A Counter example implemented with riverpod and shared_preferences

/// Providers are declared globally and specify how to create a state
final counterProvider = StateProvider((ref) => 0);

final sharedPrefs = Provider<SharedPreferences>((ref) {
  throw UnimplementedError();
});

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  final sharedPreferences = await SharedPreferences.getInstance();
  runApp(
    // Adding ProviderScope enables Riverpod for the entire project
    ProviderScope(overrides: [
      sharedPrefs.overrideWithValue(sharedPreferences),
    ], child: const MyApp()),
  );
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(home: Home());
  }
}

class Home extends ConsumerWidget {
  const Home({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return Scaffold(
      appBar: AppBar(title: const Text('Flutter101')),
      body: Center(
        child: Consumer(builder: (context, ref, _) {
          final count = ref.watch(counterProvider.state).state;
          final prefs = ref.read(sharedPrefs);
          final countPref = prefs.getInt('counter') ?? 0;
          if (count != countPref) {
            Future.delayed(Duration.zero).then(
                (value) => ref.read(counterProvider.state).state = countPref);
          }
          return Text(
            '$countPref',
            style:
                DefaultTextStyle.of(context).style.apply(fontSizeFactor: 5.0),
          );
        }),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          final prefs = ref.read(sharedPrefs);
          final countPref = (prefs.getInt('counter') ?? 0) + 1;
          prefs.setInt('counter', countPref);
          ref.read(counterProvider.state).state = countPref;
        },
        child: const Icon(Icons.add),
      ),
    );
  }
}