riverpod_memory_leak_example.dart

import 'dart:async';

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

void main() => runApp(const ProviderScope(child: MyApp()));

final userProvider = StateProvider<int>((ref) => 1);

final controllerProvider = StateNotifierProvider<ControllerNotifier, int>(
  (ref) {
    ref.watch(userProvider);
    return ControllerNotifier();
  },
);

class ControllerNotifier extends StateNotifier<int> {
  ControllerNotifier() : super(0) {
    timer = Timer.periodic(const Duration(seconds: 1), (timer) {
      if (mounted) {
        state = timer.tick;
      } else {
        // ignore: avoid_print
        print('Still ticking: ${timer.tick}');
      }
    });
  }

  late Timer timer;

  @override
  void dispose() {
    timer.cancel();
    super.dispose();
  }
}

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

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      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('Demo')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text('User: ${ref.watch(userProvider)}'),
            Text('Number: ${ref.watch(controllerProvider)}'),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          ref.read(userProvider.notifier).state++;
        },
        child: const Icon(Icons.add),
      ),
    );
  }
}