Dependency Injection in .NET MAUI

Dependency Injection in .NET MAUI

.NET MAUI uses the same Microsoft.Extensions.DependencyInjection container as ASP.NET Core. All service registration happens in MauiProgram.CreateMauiApp() on builder.Services. The container is built once at startup and is immutable thereafter.

When to Use

• Registering services, ViewModels, and Pages in MauiProgram.cs
• Choosing between AddSingleton, AddTransient, and AddScoped
• Wiring constructor injection for Pages and ViewModels
• Leveraging Shell navigation to auto-resolve DI-registered Pages
• Registering platform-specific service implementations with #if directives
• Designing interfaces for testable service layers

When Not to Use

• XAML data-binding syntax or compiled bindings — use the maui-data-binding skill
• Shell route registration and query parameters — use the maui-shell-navigation skill
• Mocking frameworks or test runners — use standard .NET testing tools (xUnit, NUnit, MSTest) and mocking libraries (NSubstitute, Moq)

Inputs

• A .NET MAUI project with a MauiProgram.cs file
• Knowledge of which services, ViewModels, and Pages need registration
• Target platforms (Android, iOS, Mac Catalyst, Windows) for conditional registrations

Workflow

1. Identify all services, ViewModels, and Pages that need to participate in dependency injection.
2. Choose the correct lifetime for each type — AddSingleton for shared services, AddTransient for Pages and ViewModels.
3. Register all types in MauiProgram.CreateMauiApp() on builder.Services, grouping by category (services, HTTP, ViewModels, Pages).
4. Register Pages as Shell routes in AppShell.xaml.cs so Shell navigation auto-resolves the full dependency graph.
5. Wire each Page to its ViewModel via constructor injection, assigning the ViewModel as BindingContext.
6. Add platform-specific registrations with #if directives, ensuring every target platform is covered or has a fallback.
7. Verify resolution works by running the app and confirming no null dependencies or missing-registration exceptions at runtime.

Lifetime Selection

| Lifetime | When to Use | Typical Types |