Flutter 튜토리얼 67편: 패키지 개발하기

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네이티브 코드가 필요한가?
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├── 아니오 → Dart 패키지
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└── 예 → C/C++ 라이브러리인가?
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    ├── 예 → FFI 패키지
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    └── 아니오 → 플러그인 패키지

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name: my_utils
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description: A collection of useful utility functions.
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version: 1.0.0
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homepage: https://github.com/username/my_utils
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environment:
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  sdk: ^3.0.0
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  flutter: ">=3.0.0"
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dependencies:
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  flutter:
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    sdk: flutter
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dev_dependencies:
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  flutter_test:
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    sdk: flutter
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  flutter_lints: ^5.0.0

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my_plugin/
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├── lib/
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│   ├── my_plugin.dart           # Dart API
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│   ├── my_plugin_method_channel.dart
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│   └── my_plugin_platform_interface.dart
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├── android/
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│   └── src/main/kotlin/.../MyPluginPlugin.kt
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├── ios/
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│   └── Classes/MyPluginPlugin.swift
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├── example/                      # 예제 앱
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└── pubspec.yaml

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import 'my_plugin_platform_interface.dart';
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class MyPlugin {
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  Future<String?> getPlatformVersion() {
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    return MyPluginPlatform.instance.getPlatformVersion();
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  }
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}

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import 'package:plugin_platform_interface/plugin_platform_interface.dart';
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import 'my_plugin_method_channel.dart';
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abstract class MyPluginPlatform extends PlatformInterface {
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  MyPluginPlatform() : super(token: _token);
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  static final Object _token = Object();
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  static MyPluginPlatform _instance = MethodChannelMyPlugin();
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  static MyPluginPlatform get instance => _instance;
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  static set instance(MyPluginPlatform instance) {
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    PlatformInterface.verifyToken(instance, _token);
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    _instance = instance;
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  }
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  Future<String?> getPlatformVersion() {
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    throw UnimplementedError('getPlatformVersion() has not been implemented.');
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  }
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}

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package com.example.my_plugin
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import io.flutter.embedding.engine.plugins.FlutterPlugin
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import io.flutter.plugin.common.MethodCall
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import io.flutter.plugin.common.MethodChannel
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import io.flutter.plugin.common.MethodChannel.MethodCallHandler
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import io.flutter.plugin.common.MethodChannel.Result
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class MyPluginPlugin: FlutterPlugin, MethodCallHandler {
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  private lateinit var channel : MethodChannel
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  override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) {
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    channel = MethodChannel(binding.binaryMessenger, "my_plugin")
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    channel.setMethodCallHandler(this)
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  }
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  override fun onMethodCall(call: MethodCall, result: Result) {
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    if (call.method == "getPlatformVersion") {
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      result.success("Android ${android.os.Build.VERSION.RELEASE}")
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    } else {
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      result.notImplemented()
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    }
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  }
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  override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
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    channel.setMethodCallHandler(null)
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  }
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}

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import Flutter
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import UIKit
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public class MyPluginPlugin: NSObject, FlutterPlugin {
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  public static func register(with registrar: FlutterPluginRegistrar) {
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    let channel = FlutterMethodChannel(
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      name: "my_plugin",
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      binaryMessenger: registrar.messenger()
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    )
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    let instance = MyPluginPlugin()
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    registrar.addMethodCallDelegate(instance, channel: channel)
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  }
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  public func handle(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
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    switch call.method {
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    case "getPlatformVersion":
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      result("iOS " + UIDevice.current.systemVersion)
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    default:
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      result(FlutterMethodNotImplemented)
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    }
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  }
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}

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# url_launcher/pubspec.yaml (메인 패키지)
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dependencies:
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  url_launcher_platform_interface: ^2.0.0
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  url_launcher_android: ^6.0.0
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  url_launcher_ios: ^6.0.0
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  url_launcher_web: ^2.0.0
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  # ...

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# url_launcher_android/pubspec.yaml (Android 구현)
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dependencies:
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  flutter:
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    sdk: flutter
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  url_launcher_platform_interface: ^2.0.0
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flutter:
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  plugin:
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    implements: url_launcher
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    platforms:
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      android:
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        package: io.flutter.plugins.urllauncher
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        pluginClass: UrlLauncherPlugin

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# my_utils
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A collection of useful utility functions for Flutter.
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## Features
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- String manipulation utilities
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- Date formatting helpers
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- Currency formatters
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## Getting started
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Add this to your `pubspec.yaml`:
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```yaml
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dependencies:
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  my_utils: ^1.0.0

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import 'package:my_utils/my_utils.dart';
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void main() {
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  final result = capitalize('hello');
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  print(result); // Hello
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}

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**CHANGELOG.md 작성**:
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```markdown
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## 1.1.0
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- Added `toCamelCase` function
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- Fixed edge case in `capitalize` for empty strings
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## 1.0.0
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- Initial release
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- Added `capitalize` function
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- Added `formatDate` function

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flutter:
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  plugin:
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    platforms:
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      android:
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        package: com.example.my_plugin
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        pluginClass: MyPluginPlugin
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      ios:
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        pluginClass: MyPluginPlugin
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      web:  # 새로 추가됨
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        pluginClass: MyPluginWeb
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        fileName: my_plugin_web.dart