$ flutter build ios --debug --no-codesign
$ flutter build apk --debug

$ flutter build ios --debug --flavor development --dart-define=FLAVOR=development --no-codesign
$ flutter build apk --debug --flavor development --dart-define=FLAVOR=development

import 'dart:async';

import 'package:enum_to_string/enum_to_string.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_crashlytics/firebase_crashlytics.dart';
import 'package:flutter/material.dart';
import 'package:hooks_riverpod/all.dart';

enum Flavor {
  development,
  production,
}

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  // flavor
  final currentFlavor = EnumToString.fromString(
    Flavor.values,
    const String.fromEnvironment('FLAVOR'),
  );
  assert(currentFlavor != null);

  // Firebase
  await Firebase.initializeApp();

  // Crashlytics
  FlutterError.onError = (details) {
    FlutterError.dumpErrorToConsole(details);
    FirebaseCrashlytics.instance.recordFlutterError(details);
  };

  runZonedGuarded(
    () => runApp(ProviderScope(child: App())),
    FirebaseCrashlytics.instance.recordError,
  );
}

# fvm
.fvm/flutter_sdk

# vscode
.vscode/settings.json #if needed

{
    "dart.flutterSdkPaths": [
        ".fvm/flutter_sdk",
    ],
}

import 'dart:io';
import 'package:flutter/services.dart';
import 'package:path_provider/path_provider.dart';

// json
final json = await rootBundle.loadString(Assets.json.fruits);

// pdf
final pdf = await rootBundle.load(Assets.pdf.manual);

import 'dart:io';
import 'package:flutter/services.dart';
import 'package:path_provider/path_provider.dart';

final tempDir = await getTemporaryDirectory();
final tempFile = File('${tempDir.path}/copy.pdf');
final pdfData = await rootBundle.load(Assets.pdf.manual);
await tempFile.writeAsBytes(pdfData.buffer.asUint8List(), flush: true);
prnt(tempFile.path); // Get pdf file path

// ...

PDFView(
  filePath: pdfFIlePath,
 ...
)

$ dart --no-sound-null-safety run
$ flutter run --no-sound-null-safety

import 'dart:convert';
import 'dart:io';

final response = await FirebaseStorage.instance
  .ref()
  .child('path/to/data.json')
  .getData();
final jsonData = json.decode(utf8.decode(response));

$ flutter pub run build_runner build --delete-conflicting-outputs

// Example from riverpod
Widget build(BuildContext context) {
  return ProviderListener<StateController<int>>(
    provider: counterProvider,
    onChange: (context, counter) {
      if (counter.state == 5) {
        showDialog(...);
      }
    },
    child: Whatever(),
  );
}

Widget build(BuildContext context) {
  return useProvider(authStreamProvider).whenData((auth) {
    if (auth == null) {
      return WidgetForNotLoggedInUser();
    } else {
      return WidgetForLoggedInUser();
  }
}

final _lock = Lock();
Future<void> updateArticles(List<Article> articles) async {
  await _lock.synchronized(() {
    state = state.copyWith(
      articles: [...state.articles, ...articles].toList(),
    );
  });
}

MaterialApp(
  onGenerateRoute: (settings) => MaterialWithModalsPageRoute(
    builder: (context) => InitialPage(),
  ),
);

MaterialApp(
+   onGenerateRoute: (settings) => MaterialWithModalsPageRoute(
+     builder: (context) => InitialPage(),
+   ),
-   home: InitialPage()
);

final userStreamProvider = StreamProvider<User?>((ref) {
  ...
})

final userProvider = StateProvider<User?>((ref) {
  return ref.watch(userStreamProvider).maybeWhen(
    data: (user) => user,
    orElse: () => null,
});
======
(使用例)
final user = ref.watch(userProvider)

final postsStreamProvider = StreamProvider<List<Post>>((ref) {
  final user = ref.watch(userProvider);
  return user != null : repository.listenPosts(userId: user.id) : Stream.empty();
})

final user = ref.watch(userStreamProvider).value; 

final postsStreamProvider = StreamProvider<List<Post>>((ref) {
  final user = ref.watch(userStreamProvider).value;
  return user != null : repository.listenPosts(userId: user.id) : Stream.empty();
})

final articleDetailNotifier = StateNotifierProvider.family.autoDispose<ArticleDetailNotifier, ArticleDetailState, String>((ref, articleId) {
  return ArticleDetailNotifier(
    repository: ref.watch(articleRepositoryProvider),
    articleId: articleId
  );
});

class ArticleDetailNotifier<...> {
  // 省略
}

class ArticleDetailPage extends ConsumerWidget {
  const ArticleDetailPage({required this.articleId});

  final String articleId;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final article = ref.wach(articleDetailNotifier(articleId).select((s) => s.article));
    return ...;
  }
}

// 遷移処理
Navigator.of(context).push(
  MaterialPageRoute(builder: (_) {
    ProviderScope(
      overrides: [
         articleIdProvider.overrideWithValue(articleId),
      ],
      child: const ArticleDetailPage();
  },
);

// Provider周り
final articleIdProvider = Provider<String>((ref) => throw Exception('not initialized'));
final articleDetailNotifier = StateNotifierProvider.autoDispose<ArticleDetailNotifier, ArticleDetailState>(
  (ref) {
    return ArticleDetailNotifier(
      repository: ref.watch(articleRepositoryProvider),
      articleId: ref.watch(articleIdProvider)
    );
  },
  dependencies: [articleIdProvider, articleIdProvider],
);

class ArticleDetailNotifier<...> {
  // 省略
}

// PageWidget
class ArticleDetailPage extends ConsumerWidget {
  const ArticleDetailPage();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final article = ref.wach(articleDetailNotifier.select((s) => s.article));
    return ...;
  }
}

extension on String {
 String prefix(int count) => substring(0, count.clamp(0, length));
 String suffix(int count) => substring((length - count).clamp(0, length), length);
}

void main() {
  print('abcde'.prefix(-1));
  print('abcde'.prefix(0));
  print('abcde'.prefix(1));
  print('abcde'.prefix(2));
  print('abcde'.prefix(3));
  print('abcde'.prefix(4));
  print('abcde'.prefix(5));
  print('abcde'.prefix(6));
print('-----------------');
  print('abcde'.suffix(-1));
  print('abcde'.suffix(0));
  print('abcde'.suffix(1));
  print('abcde'.suffix(2));
  print('abcde'.suffix(3));
  print('abcde'.suffix(4));
  print('abcde'.suffix(5));
  print('abcde'.suffix(6));
}

// e.g. inside StateNotifier's initializer

ref.listen(postsStreamProvider, (_, <AsyncValue<List<Post>>> current) {
  state = state.copyWith(posts: current.value ?? []);
}, fireImmediately: true);