MyMauiApp/
├── Platforms/
│   ├── Android/
│   │   └── MainActivity.cs
│   ├── iOS/
│   │   └── AppDelegate.cs
│   ├── Windows/
│   │   └── App.xaml
│   └── MacCatalyst/
├── Resources/
│   ├── Images/        ← 이미지 한 번만 넣으면 자동 리사이징!
│   ├── Fonts/
│   └── Styles/
├── App.xaml           ← 공유 앱 진입점
├── MainPage.xaml      ← 공유 UI
└── MauiProgram.cs     ← 앱 설정 (DI 컨테이너 등)

// MAUI 핸들러 커스터마이징 예시
// Entry 컨트롤의 밑줄 제거 (Android)
Microsoft.Maui.Handlers.EntryHandler.Mapper.AppendToMapping(
    "NoUnderline", (handler, view) =>
    {
#if ANDROID
        handler.PlatformView.BackgroundTintList =
            Android.Content.Res.ColorStateList.ValueOf(
                Android.Graphics.Color.Transparent);
#endif
    });

<!-- MainPage.xaml -->
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:b="clr-namespace:Microsoft.AspNetCore.Components.WebView.Maui;assembly=Microsoft.AspNetCore.Components.WebView.Maui">
    <b:BlazorWebView HostPage="wwwroot/index.html">
        <b:BlazorWebView.RootComponents>
            <b:RootComponent Selector="#app" ComponentType="{x:Type local:Main}" />
        </b:BlazorWebView.RootComponents>
    </b:BlazorWebView>
</ContentPage>

// MauiProgram.cs - DI 설정
public static MauiApp CreateMauiApp()
{
    var builder = MauiApp.CreateBuilder();
    builder
        .UseMauiApp<App>()
        .ConfigureFonts(fonts =>
        {
            fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
        });

    // Blazor 서비스 등록
    builder.Services.AddMauiBlazorWebView();

    // 네이티브 서비스 등록 (DI 활용)
    builder.Services.AddSingleton<IDeviceService, DeviceService>();
    builder.Services.AddSingleton<ILocationService, LocationService>();

#if DEBUG
    builder.Services.AddBlazorWebViewDeveloperTools();
#endif

    return builder.Build();
}

<!-- 기존 웹앱 래핑 -->
<WebView Source="https://yourwebapp.com"
         HorizontalOptions="FillAndExpand"
         VerticalOptions="FillAndExpand" />

// ViewModel 예시 (CommunityToolkit.Mvvm 활용)
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;

public partial class MainViewModel : ObservableObject
{
    [ObservableProperty]
    private string _userName = string.Empty;

    [ObservableProperty]
    private bool _isLoading;

    [ObservableProperty]
    private ObservableCollection<Product> _products = new();

    [RelayCommand]
    private async Task LoadProductsAsync()
    {
        IsLoading = true;
        try
        {
            var result = await _productService.GetProductsAsync();
            Products = new ObservableCollection<Product>(result);
        }
        finally
        {
            IsLoading = false;
        }
    }
}

// 서비스 인터페이스 정의
public interface IWeatherService
{
    Task<WeatherData> GetCurrentWeatherAsync(double lat, double lon);
}

// 플랫폼별 구현 (필요한 경우)
public class WeatherService : IWeatherService
{
    private readonly HttpClient _httpClient;

    public WeatherService(HttpClient httpClient)
    {
        _httpClient = httpClient;
    }

    public async Task<WeatherData> GetCurrentWeatherAsync(double lat, double lon)
    {
        var response = await _httpClient.GetFromJsonAsync<WeatherData>(
            $"api/weather?lat={lat}&lon={lon}");
        return response ?? new WeatherData();
    }
}

// MauiProgram.cs에서 등록
builder.Services.AddHttpClient<IWeatherService, WeatherService>(client =>
{
    client.BaseAddress = new Uri("https://api.yourweather.com/");
});

<!-- AppShell.xaml -->
<Shell xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
       xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
       xmlns:views="clr-namespace:MyApp.Views">

    <TabBar>
        <Tab Title="홈" Icon="home.png">
            <ShellContent ContentTemplate="{DataTemplate views:HomePage}" Route="home"/>
        </Tab>
        <Tab Title="검색" Icon="search.png">
            <ShellContent ContentTemplate="{DataTemplate views:SearchPage}" Route="search"/>
        </Tab>
        <Tab Title="프로필" Icon="profile.png">
            <ShellContent ContentTemplate="{DataTemplate views:ProfilePage}" Route="profile"/>
        </Tab>
    </TabBar>
</Shell>

// 방법 1: 컴파일러 지시문 (#if)
public void ConfigurePlatform()
{
#if ANDROID
    // Android 전용 코드
    Android.App.Application.Context.GetSystemService(...);
#elif IOS
    // iOS 전용 코드
    UIKit.UIApplication.SharedApplication.StatusBarStyle = ...;
#elif WINDOWS
    // Windows 전용 코드
#endif
}

// 방법 2: DeviceInfo 런타임 체크
if (DeviceInfo.Platform == DevicePlatform.iOS)
{
    // iOS에서만 실행
}

// 방법 3: 부분 클래스 (Partial Class) - 권장
// Platforms/Android/MyService.cs
public partial class MyService
{
    public partial void DoAndroidThing()
    {
        // Android 구현
    }
}

// Platforms/iOS/MyService.cs
public partial class MyService
{
    public partial void DoAndroidThing()
    {
        // iOS 구현 (같은 메서드명, 다른 구현)
    }
}

// 모델 정의
public class TodoItem
{
    [PrimaryKey, AutoIncrement]
    public int Id { get; set; }
    public string Title { get; set; } = string.Empty;
    public bool IsCompleted { get; set; }
    public DateTime CreatedAt { get; set; } = DateTime.Now;
}

// 데이터베이스 서비스
public class TodoDatabase
{
    private SQLiteAsyncConnection? _database;

    private async Task InitAsync()
    {
        if (_database is not null) return;

        var dbPath = Path.Combine(
            FileSystem.AppDataDirectory, "todo.db3");
        _database = new SQLiteAsyncConnection(dbPath,
            SQLiteOpenFlags.ReadWrite |
            SQLiteOpenFlags.Create |
            SQLiteOpenFlags.SharedCache);

        await _database.CreateTableAsync<TodoItem>();
    }

    public async Task<List<TodoItem>> GetItemsAsync()
    {
        await InitAsync();
        return await _database!.Table<TodoItem>().ToListAsync();
    }

    public async Task<int> SaveItemAsync(TodoItem item)
    {
        await InitAsync();
        return item.Id != 0
            ? await _database!.UpdateAsync(item)
            : await _database!.InsertAsync(item);
    }
}

// GPS 위치 가져오기
public async Task<Location?> GetCurrentLocationAsync()
{
    try
    {
        var request = new GeolocationRequest(
            GeolocationAccuracy.Medium,
            TimeSpan.FromSeconds(10));
        return await Geolocation.Default.GetLocationAsync(request);
    }
    catch (FeatureNotSupportedException)
    {
        // GPS 미지원 기기
        return null;
    }
    catch (PermissionException)
    {
        // 권한 없음 - 권한 요청 필요
        await RequestLocationPermission();
        return null;
    }
}

// 카메라로 사진 찍기
public async Task<FileResult?> TakePhotoAsync()
{
    if (MediaPicker.Default.IsCaptureSupported)
    {
        return await MediaPicker.Default.CapturePhotoAsync();
    }
    return null;
}

// 클립보드 복사
await Clipboard.Default.SetTextAsync("복사할 텍스트");

// 진동
Vibration.Default.Vibrate(TimeSpan.FromMilliseconds(500));

<!-- 가상화 활성화 (기본값이지만 명시적으로) -->
<CollectionView ItemsSource="{Binding Products}"
                RemainingItemsThreshold="5"
                RemainingItemsThresholdReachedCommand="{Binding LoadMoreCommand}">
    <CollectionView.ItemTemplate>
        <DataTemplate x:DataType="models:Product">
            <!-- x:DataType으로 컴파일 타임 바인딩 활성화 -->
            <Grid Padding="10">
                <Label Text="{Binding Name}" />
                <Label Text="{Binding Price, StringFormat='{0:C}'}" />
            </Grid>
        </DataTemplate>
    </CollectionView.ItemTemplate>
</CollectionView>

// 이미지 캐싱 (FFImageLoading 또는 기본 캐싱 활용)
<Image Source="{Binding ImageUrl}"
       Aspect="AspectFill"
       CachingStrategy="RecycleElement" />

// 코드에서 이미지 다운샘플링
var imageSource = ImageSource.FromUri(new Uri(imageUrl));
// 큰 이미지는 표시 크기에 맞게 리사이징 필요

// WeakReference 활용으로 메모리 누수 방지
public class MyViewModel : ObservableObject, IDisposable
{
    private readonly IDisposable _subscription;

    public MyViewModel(IEventAggregator eventAggregator)
    {
        // WeakReferenceMessenger 사용 (CommunityToolkit)
        WeakReferenceMessenger.Default
            .Register<ProductUpdatedMessage>(this, (r, m) =>
            {
                // 메시지 처리
            });
    }

    public void Dispose()
    {
        // 구독 해제 - 메모리 누수 방지
        WeakReferenceMessenger.Default.UnregisterAll(this);
        _subscription?.Dispose();
    }
}

# .github/workflows/maui-build.yml
name: MAUI Build & Deploy

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  build-android:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Setup .NET
        uses: actions/setup-dotnet@v4
        with:
          dotnet-version: '8.0.x'
      - name: Install MAUI workload
        run: dotnet workload install maui-android
      - name: Build Android
        run: dotnet build -f net8.0-android -c Release
      - name: Sign APK
        # 서명 단계 (keystore 파일 필요)
        run: |
          echo "${{ secrets.KEYSTORE_FILE }}" | base64 -d > keystore.jks
          # apksigner 명령어로 서명

  build-ios:
    runs-on: macos-latest  # iOS 빌드는 macOS 필수!
    steps:
      - uses: actions/checkout@v4
      - name: Setup .NET
        uses: actions/setup-dotnet@v4
        with:
          dotnet-version: '8.0.x'
      - name: Install MAUI workload
        run: dotnet workload install maui-ios
      - name: Build iOS
        run: dotnet build -f net8.0-ios -c Release

// HybridWebView 사용 예시 (.NET 9)
<HybridWebView x:Name="hybridWebView"
               HybridRoot="hybrid_root"
               DefaultFile="index.html"
               RawMessageReceived="OnRawMessageReceived" />

// C#에서 JavaScript 호출
await hybridWebView.InvokeJavaScriptAsync(
    "updateUserData",
    HybridWebViewJsonSerializerContext.Default.UserData,
    new[] { userData });

// JavaScript에서 C# 호출 (JS 코드)
// window.HybridWebView.SendRawMessage('{"action":"getLocation"}');