maui-blazor-development

What this skill does

# .NET MAUI Blazor Hybrid Development

Expert guidance for building cross-platform apps with .NET MAUI and Blazor.

## Implementation Workflow

### 1. Analysis Phase (Required)

Before implementation, determine:

- **App type**: Pure MAUI Blazor or MAUI + Blazor Web App (shared UI)
- **Platform targets**: Android, iOS, Windows, macOS
- **Native features needed**: Sensors, camera, file system, notifications
- **State management**: Component state, MVVM, or hybrid approach
- **Navigation pattern**: Blazor-only, Shell, or mixed navigation

### 2. Architecture Decision

| Scenario | Recommended Approach |
|----------|---------------------|
| Mobile-first with some web | `maui-blazor` template |
| Shared UI across mobile + web | `maui-blazor-web` template with RCL |
| Complex native integration | MVVM with platform services |
| Simple data-driven UI | Component state with DI services |

### 3. Project Setup

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

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

    // Register services
    builder.Services.AddSingleton<IDeviceService, DeviceService>();
    builder.Services.AddScoped<IDataService, DataService>();

    return builder.Build();
}
```

### 4. BlazorWebView Configuration

```xml
<!-- MainPage.xaml -->
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             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>
```

## Core Patterns

### Dependency Injection

| Lifetime | Use Case |
|----------|----------|
| `AddSingleton<T>` | App-wide state, device services, settings |
| `AddScoped<T>` | Per-BlazorWebView instance state |
| `AddTransient<T>` | Stateless utilities, factories |

```csharp
// Interface for platform-specific implementation
public interface IDeviceService
{
    string GetDeviceModel();
    Task<bool> HasPermissionAsync(string permission);
}

// Platform implementation registered in MauiProgram.cs
builder.Services.AddSingleton<IDeviceService, DeviceService>();
```

### Component Lifecycle

```csharp
@code {
    [Parameter] public string Id { get; set; } = "";

    // Called once when component initializes
    protected override async Task OnInitializedAsync()
    {
        await LoadDataAsync();
    }

    // Called when parameters change (including first render)
    protected override void OnParametersSet()
    {
        // React to parameter changes
    }

    // Called after each render
    protected override void OnAfterRender(bool firstRender)
    {
        if (firstRender)
        {
            // JS interop safe here
        }
    }
}
```

### Platform Feature Access

```csharp
// Check platform and access native features
@inject IDeviceService DeviceService

@if (DeviceInfo.Current.Platform == DevicePlatform.Android)
{
    <AndroidSpecificComponent />
}

@code {
    private async Task AccessCameraAsync()
    {
        var status = await Permissions.CheckStatusAsync<Permissions.Camera>();
        if (status != PermissionStatus.Granted)
        {
            status = await Permissions.RequestAsync<Permissions.Camera>();
        }

        if (status == PermissionStatus.Granted)
        {
            // Use camera
        }
    }
}
```

### State Updates from External Events

```csharp
@implements IDisposable
@inject IDataService DataService

<p>@message</p>

@code {
    private string message = "";

    protected override void OnInitialized()
    {
        DataService.OnDataChanged += HandleDataChanged;
    }

    private async void HandleDataChanged(object? sender, EventArgs e)
    {
        message = "Data updated!";
        await InvokeAsync(StateHasChanged); // Required for external events
    }

    public void Dispose()
    {
        DataService.OnDataChanged -= HandleDataChanged;
    }
}
```

## Reference Documentation

For detailed patterns and examples, see:

- **[Project Structure](../../references/project-structure.md)**: Solution templates, RCL setup, multi-targeting
- **[Blazor Components](../../references/blazor-components.md)**: Lifecycle, RenderFragment, EventCallback, data binding
- **[Platform Integration](../../references/platform-integration.md)**: Device APIs, permissions, platform-specific code
- **[Navigation & Routing](../../references/navigation-routing.md)**: Blazor routing, Shell, deep linking
- **[State Management](../../references/state-management.md)**: MVVM, DI patterns, CommunityToolkit.Mvvm

## Quick Reference

### Common Service Registration

```csharp
// Services
builder.Services.AddSingleton<ISettingsService, SettingsService>();
builder.Services.AddSingleton<IConnectivity>(Connectivity.Current);
builder.Services.AddSingleton<IGeolocation>(Geolocation.Default);

// ViewModels (if using MVVM)
builder.Services.AddTransient<MainViewModel>();
builder.Services.AddTransient<SettingsViewModel>();

// Pages with DI
builder.Services.AddTransient<MainPage>();
```

### Platform Checks

```csharp
// Runtime platform check
if (DeviceInfo.Current.Platform == DevicePlatform.iOS) { }
if (DeviceInfo.Current.Platform == DevicePlatform.Android) { }
if (DeviceInfo.Current.Platform == DevicePlatform.WinUI) { }
if (DeviceInfo.Current.Platform == DevicePlatform.macOS) { }

// Compile-time platform check
#if ANDROID
    // Android-specific code
#elif IOS
    // iOS-specific code
#elif WINDOWS
    // Windows-specific code
#endif
```

### Navigation Patterns

```csharp
// Blazor navigation (within BlazorWebView)
@inject NavigationManager Navigation
Navigation.NavigateTo("/details/123");

// MAUI navigation (to other pages)
await Navigation.PushAsync(new SettingsPage());
await Shell.Current.GoToAsync("//settings");
```