How do you handle platform-specific services in a project using both MvvmCross and CSLA.net

Understanding MvvmCross and CSLA.NET

- MvvmCross: This framework is designed for cross-platform development, allowing you to share code across different platforms like iOS, Android, and Windows. It uses the Model-View-ViewModel (MVVM) pattern and provides features like Inversion of Control (IoC) for managing dependencies[1][3].

- CSLA.NET: This is a framework for building business applications, providing features like business object management, validation, and data binding. It can be used alongside MVVM patterns to manage business logic[6].

Handling Platform-Specific Services

1. Define Platform-Agnostic Interfaces**

First, define interfaces for your platform-specific services in the core project. These interfaces should be abstract enough to be implemented differently on each platform. For example, if you need a service to display platform-specific dialogs, define an interface like `IPlatformSpecificDialogs` in your core project:

csharp
public interface IPlatformSpecificDialogs
{
    void Alert(string message, string title, string okButtonText);
}

2. Implement Platform-Specific Services**

Implement these interfaces in platform-specific projects. For instance, you would implement `IPlatformSpecificDialogs` differently for iOS and Android:

- iOS Implementation:

csharp
  public class IOSDialogs : IPlatformSpecificDialogs
  {
      public void Alert(string message, string title, string okButtonText)
      {
          // Use iOS-specific dialog APIs
      }
  }
  

- Android Implementation:

csharp
  public class AndroidDialogs : IPlatformSpecificDialogs
  {
      public void Alert(string message, string title, string okButtonText)
      {
          // Use Android-specific dialog APIs
      }
  }
  

3. Register Services with MvvmCross IoC**

In the `Setup` class of each platform project, register the platform-specific implementations with the MvvmCross IoC container. This allows the core logic to resolve these services without knowing the specific implementation:

- iOS Setup:

csharp
  public class Setup : MvxSetup
  {
      protected override void InitializeFirstChance()
      {
          Mvx.IoCProvider.RegisterType();
      }
  }
  

- Android Setup:

csharp
  public class Setup : MvxSetup
  {
      protected override void InitializeFirstChance()
      {
          Mvx.IoCProvider.RegisterType();
      }
  }
  

4. Use Services in ViewModels**

In your ViewModels, you can now inject and use these platform-specific services through constructor injection:

csharp
public class MyViewModel : MvxViewModel
{
    private readonly IPlatformSpecificDialogs _dialogs;

    public MyViewModel(IPlatformSpecificDialogs dialogs)
    {
        _dialogs = dialogs;
    }

    public void ShowAlert()
    {
        _dialogs.Alert("Hello", "Title", "OK");
    }
}

5. Integrate with CSLA.NET**

When integrating with CSLA.NET, ensure that your business objects are properly validated and managed according to CSLA.NET principles. You can use CSLA.NET's validation features within your ViewModels or business logic layers, while still leveraging MvvmCross for cross-platform UI management[6].

Conclusion

By defining platform-agnostic interfaces, implementing them in platform-specific projects, and registering these implementations with MvvmCross's IoC container, you can effectively handle platform-specific services in a project that uses both MvvmCross and CSLA.NET. This approach allows for a clean separation of concerns and facilitates cross-platform development.