Flutterで言語パックを作り、多言語対応する（easy_localization）

flutter pub add easy_localization

dependencies:
  easy_localization: version

assets:
  - assets/translations/

...
		<key>CFBundleLocalizations</key>
		<array>
			<string>en_US</string>
			<string>ko_KR</string>
		</array>
...

import 'package:flutter/material.dart';
import 'package:easy_localization/easy_localization.dart';
import 'package:example_project/home_page.dart';
 
void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await EasyLocalization.ensureInitialized(); // 언어 팩 초기화
 
  runApp(
    EasyLocalization(
        // 언어 팩 설정
        supportedLocales: const [Locale('en', 'US'), Locale('ko', 'KR')],
        path: 'assets/translations',
        fallbackLocale: const Locale('en', 'US'), // 휴대폰 설정이 없을 시 기본 언어
        child: const MyApp()),
  );
}
 
class MyApp extends StatelessWidget {
  const MyApp({super.key});
 
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        localizationsDelegates: context.localizationDelegates,
        supportedLocales: context.supportedLocales,
        locale: context.locale,
        home: const HomePage());
  }
}
 

{
	"hello": "Hello, world!"
}

{
	"hello": "안녕하세요!"
}

import 'package:easy_localization/easy_localization.dart';
import 'package:flutter/material.dart';
 
class HomePage extends StatelessWidget {
  const HomePage({super.key});
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              context.tr('hello'), // 언어 팩 데이터 사용
              style: const TextStyle(fontSize: 20),
            ),
            ElevatedButton( // 한국어 버튼
              onPressed: () {
                context.setLocale(const Locale('ko', 'KR'));
              },
              child: const Text('한국어'),
            ),
            ElevatedButton( // 영어 버튼
              onPressed: () {
                context.setLocale(const Locale('en', 'US'));
              },
              child: const Text('영어'),
            ),
          ],
        ),
      ),
    );
  }
}

{
	"hello": "Hello, {}!",
	"hello_friends": "Hello, {}, {}!",
	"hello_name": "Hello, {name}!",
	"hello_name_age": "Hello, {name}! You are {age} years old.",
	"hello_friends_name": "Hello, {}, {name}!",
}

// ...
context.tr('hello', args: ['John']);
context.tr('hello_friends', args: ['John', 'Jane']);
context.tr('hello_name', namedArgs: {'name': 'John'});
context.tr('hello_name_age', namedArgs: {'name': 'John', 'age': 20});
context.tr('hello_friends_name', args: ['John'], namedArgs: {'name': 'Jane'});
// ...

{
	"gender":{
		"male":"Hi man ;) {}",
		"female":"Hello girl :) {}",
		"other":"Hello {}"
	}
}

// ...
context.tr("gender", gender: _gender ? "female" : "male");
// ...

{
  "money": {
    "zero": "You not have money",
    "one": "You have {} dollar",
    "many": "You have {} dollars",
    "other": "You have {} dollars"
  },
	"money_named_args": { // 이름 지정
    "zero": "{name} has no money",
    "one": "{name} has {money} dollar",
    "many": "{name} has {money} dollars",
    "other": "{name} has {money} dollars"
  }
}

// ...
context.plural('money', 0);
context.plural('money', 1);
context.plural('money', 2);
context.plural('money_named_args', 10.23, namedArgs: {'name': 'Jane'}, name: 'money') // 이름 지정
// ...

{
  "example": {
    "hello": "Hello",
    "world": "World!",
    "helloWorld": "@:example.hello @:example.world" // 이렇게 사용합니다.
  }
}

// ...
context.tr('example.hello'); // 결과: Hello
context.tr('example.world'); // 결과: World!
context.tr('example.helloWorld'); // 결과: Hello World!
// ...

// ...
context.resetLocale();
// ...

// ...
context.deviceLocale.toString() // 결과: en_US
// ...

// ...
context.setLocale(Locale('ko', 'KR')); // 한국어로 설정
// ...

Note: intl is pinned to version 0.19.0 by flutter_localizations from the flutter SDK.
See https://dart.dev/go/sdk-version-pinning for details.
 
The current Dart SDK version is 3.5.4.
 
Because easy_localization >=2.3.4-nullsafety <3.0.0-dev.0 depends on flutter_localizations from sdk and easy_localization >=3.0.0-dev.0 <3.0.0-nullsafety doesn't support null safety,
  easy_localization >=2.3.4-nullsafety <3.0.0-nullsafety requires flutter_localizations from sdk.
And because easy_localization <2.3.4-nullsafety doesn't support null safety, easy_localization <3.0.0-nullsafety requires flutter_localizations from sdk.
And because easy_localization >=3.0.0-nullsafety depends on flutter_localizations from sdk which depends on intl 0.19.0, every version of easy_localization requires intl 0.19.0.
So, because nftcam_flutter depends on both intl ^0.20.1 and easy_localization any, version solving failed.
 
The lower bound of "sdk: '>=2.0.0-dev.68.0 <3.0.0'" must be 2.12.0 or higher to enable null safety.
For details, see https://dart.dev/null-safety
 
The lower bound of "sdk: '>=2.7.0 <3.0.0'" must be 2.12.0 or higher to enable null safety.
For details, see https://dart.dev/null-safety

flutter channel master
flutter upgrade

// ...
const newLocale = Locale('ko', 'KR');
await context.setLocale(newLocale);
Get.updateLocale(newLocale);
// ...