MvvmCross is a cross-platform framework that facilitates the development of applications using the Model-View-ViewModel (MVVM) pattern. It allows developers to create loosely coupled, maintainable, and testable mobile solutions by separating the application logic into two main parts: the Core project and the UI project.
Core Project
The Core project is typically a .NET Standard library that contains all the shared code, including:- ViewModels: These are responsible for handling user interactions and business logic.
- Models: Represent the data structures used throughout the application.
- Services: Provide access to data, web services, or other external resources.
- Converters: Used for data type conversions.
- App Class: This is responsible for initializing the application's business logic and view models. It also handles the registration of custom objects in the Inversion of Control (IoC) container.
- AppStart: Optionally used to determine which view model to present first when the application starts.
UI Project
The UI project is platform-specific and contains the user interface elements and platform-specific code. For each target platform (e.g., iOS, Android), there is a separate UI project. These projects include:- Views: Each view is responsible for presenting a corresponding view model. Views are designed using native platform tools (e.g., XAML for Xamarin.Forms, AXML for Android).
- Native Application Handler: This handles native lifecycle events. For example, on Android, it would be a `MainActivity` or `MainApplication` class, while on iOS, it would be an `AppDelegate` class.
- Setup Class: This is responsible for bootstrapping MvvmCross and registering platform-specific services. It initializes the MvvmCross framework and sets up the IoC container with platform-specific implementations.
Interaction Between Core and UI Projects
The interaction between the Core and UI projects in MvvmCross is facilitated by the MVVM pattern and the framework's IoC container. Here's how they interact:- ViewModel Binding: The UI projects use MvvmCross to bind views to view models. This is typically done using a naming convention or by decorating views with attributes like `[MvxViewFor(typeof(HomeViewModel))]`.
- Service Injection: The Core project defines interfaces for services that are implemented differently on each platform. These services are registered in the IoC container and injected into view models, allowing for platform-specific functionality without duplicating code.
- Navigation and Presentation: MvvmCross provides mechanisms for navigating between view models and presenting views. The framework uses presenters (e.g., `IMvxIosViewPresenter`, `IMvxAndroidViewPresenter`) to manage how views are displayed on each platform.
By separating the application logic into Core and UI projects, MvvmCross enables developers to maximize code reuse across platforms while still allowing for platform-specific customization and optimization[1][3][5].
Citations:[1] https://www.mvvmcross.com/documentation/getting-started/mvvmcross-overview
[2] https://canbilgin.wordpress.com/tag/mvvmcross/
[3] https://leaware.com/creating-cross-platform-xamarin-applications-using-the-mvvmcross-framework/
[4] https://www.mvvmcross.com/documentation/advanced/customizing-using-App-and-Setup
[5] https://www.suneco.nl/blogs/boost-your-xamarin-native-projects-with-mvvmcross/
[6] https://learn.microsoft.com/en-us/archive/msdn-magazine/2014/august/windows-phone-build-mvvm-apps-with-xamarin-and-mvvmcross
[7] https://www.mvvmcross.com/documentation/tutorials/tipcalc/the-core-project
[8] https://canbilgin.wordpress.com/2017/03/26/xamarin-forms-application-with-mvvmcross/