MAUI Architecture

.NET Multi-platform App UI (MAUI) is a cross-platform framework for creating native mobile and desktop applications with C# and XAML. It's the evolution of Xamarin.Forms, offering a more unified approach to app development across multiple platforms.

Core Components of MAUI

MAUI's architecture is designed for efficiency, extensibility, and platform consistency. It consists of several key components that work together:

1. .NET Runtime and Base Class Library (BCL)

At the foundation of MAUI is the .NET runtime environment. This includes the Common Language Runtime (CLR) and the Base Class Library (BCL), which provides fundamental types and services used by all .NET applications. MAUI leverages the latest .NET features and performance improvements.

2. .NET MAUI Essentials

.NET MAUI Essentials is a .NET library that provides cross-platform APIs for accessing native device features. These APIs are crucial for interacting with device hardware and platform-specific functionalities, such as:

Device Information (OS version, model, etc.)
Sensors (accelerometer, gyroscope)
Connectivity (Wi-Fi, cellular)
Geolocation
Preferences (key-value storage)
Secure Storage

By abstracting these platform-specific calls, Essentials allows you to write a single code path for accessing these common features.

3. .NET MAUI Controls

MAUI provides a rich set of pre-built UI controls that abstract the native UI elements of each target platform. When you use a MAUI control, such as a Button or Entry, the framework maps it to the corresponding native control on iOS, Android, macOS, or Windows. This ensures a native look and feel for your application.

These controls are implemented using a combination of C# and XAML, allowing for flexible UI design.

4. Handlers (The Bridge to Native UI)

This is a significant architectural change from Xamarin.Forms. In MAUI, the concept of Handlers is introduced. A Handler is responsible for mapping a MAUI control to its native platform equivalent. Each MAUI control has a corresponding Handler that manages its lifecycle and properties.

When a MAUI control is rendered:

The MAUI control's properties are set.
The Handler associated with that control receives these properties.
The Handler creates and configures the native UI element on the target platform.
The Handler also manages the communication of events back from the native platform to the MAUI control.

This approach provides greater flexibility and extensibility, allowing developers to customize or create new platform-specific renderers more easily.

5. Platform-Specific Projects

A .NET MAUI project contains platform-specific projects for each target you wish to build for (e.g., iOS, Android, Windows, macOS). These projects contain the necessary platform-specific assets, configurations, and entry points for your application.

The shared C# and XAML code resides in the main .NET MAUI project, and the platform-specific projects integrate with the .NET MAUI framework to build and run the application on their respective operating systems.

Architectural Diagram

Figure 1: Conceptual MAUI Architecture

The diagram illustrates how the different layers of MAUI interact. The shared application code (UI and logic) is built on top of .NET MAUI Essentials and Controls. Handlers act as the crucial translation layer, converting MAUI abstractions into native platform UI elements and events.

Key Advantages of MAUI Architecture

Code Reusability: Write your UI and business logic once and deploy it across multiple platforms.
Native Performance: MAUI compiles to native code, delivering performance comparable to platform-specific applications.
Extensibility: The Handler architecture makes it easier to customize controls or implement custom platform-specific behaviors.
Unified Development: A single project structure and codebase simplify the development and maintenance process.
Modern .NET: Built on the latest .NET platform, benefiting from performance improvements, new language features, and a robust ecosystem.

Note: .NET MAUI is the recommended evolution of Xamarin.Forms. While Xamarin.Forms applications can be migrated, MAUI offers a more streamlined and powerful architecture for cross-platform development.

Tip: Understanding the role of Handlers is key to advanced customization in .NET MAUI. Explore how to create custom handlers to tailor the look and behavior of your UI elements on specific platforms.

This architecture enables developers to build high-quality, performant applications for a wide range of devices and operating systems from a single, unified codebase.