Add localization support with flutter_localizations

l10n.yaml

@@ -0,0 +1,3 @@
+arb-dir: lib/l10n
+template-arb-file: app_en.arb
+output-localization-file: app_localizations.dart

lib/l10n/app_en.arb

@@ -0,0 +1,7 @@
+{
+  "@@locale": "en",
+  "appTitle": "Tattoo",
+  "@appTitle": {
+    "description": "The application title"
+  }
+}

lib/l10n/app_localizations.dart

@@ -0,0 +1,140 @@
+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
+import 'package:intl/intl.dart' as intl;
+
+import 'app_localizations_en.dart';
+import 'app_localizations_zh.dart';
+
+// ignore_for_file: type=lint
+
+/// Callers can lookup localized strings with an instance of AppLocalizations
+/// returned by `AppLocalizations.of(context)`.
+///
+/// Applications need to include `AppLocalizations.delegate()` in their app's
+/// `localizationDelegates` list, and the locales they support in the app's
+/// `supportedLocales` list. For example:
+///
+/// ```dart
+/// import 'l10n/app_localizations.dart';
+///
+/// return MaterialApp(
+///   localizationsDelegates: AppLocalizations.localizationsDelegates,
+///   supportedLocales: AppLocalizations.supportedLocales,
+///   home: MyApplicationHome(),
+/// );
+/// ```
+///
+/// ## Update pubspec.yaml
+///
+/// Please make sure to update your pubspec.yaml to include the following
+/// packages:
+///
+/// ```yaml
+/// dependencies:
+///   # Internationalization support.
+///   flutter_localizations:
+///     sdk: flutter
+///   intl: any # Use the pinned version from flutter_localizations
+///
+///   # Rest of dependencies
+/// ```
+///
+/// ## iOS Applications
+///
+/// iOS applications define key application metadata, including supported
+/// locales, in an Info.plist file that is built into the application bundle.
+/// To configure the locales supported by your app, you’ll need to edit this
+/// file.
+///
+/// First, open your project’s ios/Runner.xcworkspace Xcode workspace file.
+/// Then, in the Project Navigator, open the Info.plist file under the Runner
+/// project’s Runner folder.
+///
+/// Next, select the Information Property List item, select Add Item from the
+/// Editor menu, then select Localizations from the pop-up menu.
+///
+/// Select and expand the newly-created Localizations item then, for each
+/// locale your application supports, add a new item and select the locale
+/// you wish to add from the pop-up menu in the Value field. This list should
+/// be consistent with the languages listed in the AppLocalizations.supportedLocales
+/// property.
+abstract class AppLocalizations {
+  AppLocalizations(String locale)
+    : localeName = intl.Intl.canonicalizedLocale(locale.toString());
+
+  final String localeName;
+
+  static AppLocalizations? of(BuildContext context) {
+    return Localizations.of<AppLocalizations>(context, AppLocalizations);
+  }
+
+  static const LocalizationsDelegate<AppLocalizations> delegate =
+      _AppLocalizationsDelegate();
+
+  /// A list of this localizations delegate along with the default localizations
+  /// delegates.
+  ///
+  /// Returns a list of localizations delegates containing this delegate along with
+  /// GlobalMaterialLocalizations.delegate, GlobalCupertinoLocalizations.delegate,
+  /// and GlobalWidgetsLocalizations.delegate.
+  ///
+  /// Additional delegates can be added by appending to this list in
+  /// MaterialApp. This list does not have to be used at all if a custom list
+  /// of delegates is preferred or required.
+  static const List<LocalizationsDelegate<dynamic>> localizationsDelegates =
+      <LocalizationsDelegate<dynamic>>[
+        delegate,
+        GlobalMaterialLocalizations.delegate,
+        GlobalCupertinoLocalizations.delegate,
+        GlobalWidgetsLocalizations.delegate,
+      ];
+
+  /// A list of this localizations delegate's supported locales.
+  static const List<Locale> supportedLocales = <Locale>[
+    Locale('en'),
+    Locale('zh'),
+  ];
+
+  /// The application title
+  ///
+  /// In en, this message translates to:
+  /// **'Tattoo'**
+  String get appTitle;
+}
+
+class _AppLocalizationsDelegate
+    extends LocalizationsDelegate<AppLocalizations> {
+  const _AppLocalizationsDelegate();
+
+  @override
+  Future<AppLocalizations> load(Locale locale) {
+    return SynchronousFuture<AppLocalizations>(lookupAppLocalizations(locale));
+  }
+
+  @override
+  bool isSupported(Locale locale) =>
+      <String>['en', 'zh'].contains(locale.languageCode);
+
+  @override
+  bool shouldReload(_AppLocalizationsDelegate old) => false;
+}
+
+AppLocalizations lookupAppLocalizations(Locale locale) {
+  // Lookup logic when only language code is specified.
+  switch (locale.languageCode) {
+    case 'en':
+      return AppLocalizationsEn();
+    case 'zh':
+      return AppLocalizationsZh();
+  }
+
+  throw FlutterError(
+    'AppLocalizations.delegate failed to load unsupported locale "$locale". This is likely '
+    'an issue with the localizations generation tool. Please file an issue '
+    'on GitHub with a reproducible sample app and the gen-l10n configuration '
+    'that was used.',
+  );
+}

lib/l10n/app_localizations_en.dart

@@ -0,0 +1,13 @@
+// ignore: unused_import
+import 'package:intl/intl.dart' as intl;
+import 'app_localizations.dart';
+
+// ignore_for_file: type=lint
+
+/// The translations for English (`en`).
+class AppLocalizationsEn extends AppLocalizations {
+  AppLocalizationsEn([String locale = 'en']) : super(locale);
+
+  @override
+  String get appTitle => 'Tattoo';
+}

lib/l10n/app_localizations_zh.dart

@@ -0,0 +1,13 @@
+// ignore: unused_import
+import 'package:intl/intl.dart' as intl;
+import 'app_localizations.dart';
+
+// ignore_for_file: type=lint
+
+/// The translations for Chinese (`zh`).
+class AppLocalizationsZh extends AppLocalizations {
+  AppLocalizationsZh([String locale = 'zh']) : super(locale);
+
+  @override
+  String get appTitle => 'Tattoo';
+}

lib/l10n/app_zh.arb

@@ -0,0 +1,4 @@
+{
+  "@@locale": "zh",
+  "appTitle": "Tattoo"
+}

pubspec.lock

@@ -302,6 +302,11 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.0.0"
+  flutter_localizations:
+    dependency: "direct main"
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   flutter_test:
     dependency: "direct dev"
     description: flutter

pubspec.yaml

@@ -10,6 +10,8 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
+  flutter_localizations:
+    sdk: flutter
 
   cupertino_icons: 1.0.8
   dio: 5.9.0
@@ -35,3 +37,4 @@ dev_dependencies:
 
 flutter:
   uses-material-design: true
+  generate: true