Can you explain the process of registering custom objects in the IoC container using MvvmCross

Overview of MvvmCross IoC

MvvmCross uses an Inversion of Control (IoC) container to manage dependencies between objects. This container is accessible via `Mvx.IoCProvider`, which acts as a central point for registering and resolving interfaces and their implementations[5][7].

Key Classes in MvvmCross

1. App Class: Located in the core project, this class is responsible for initializing business logic and registering custom objects on the IoC container. It typically inherits from `MvxApplication`[1][2].

2. Setup Class: Found in the native UI project, this class acts as a bootstrapper for the MvvmCross system and the app itself. It can override the IoC provider if needed[1].

Registering Custom Objects

Bulk Registration by Convention

MvvmCross provides a convenient way to register classes that follow a naming convention, such as those ending with "Service". This is achieved using reflection to find and register these classes as lazy singletons:

csharp
CreatableTypes()
    .EndingWith("Service")
    .AsInterfaces()
    .RegisterAsLazySingleton();

This code iterates over all types in the assembly, finds those ending with "Service", determines their interfaces, and registers them as lazy singletons[7][9].

Manual Registration

For more control, you can manually register classes using specific methods provided by the IoC container:

- RegisterSingleton: Registers a class as a singleton, meaning the same instance is returned every time it is resolved.

csharp
  Mvx.IoCProvider.RegisterSingleton(new Foo());
  

- RegisterType: Registers a class to create a new instance each time it is resolved.

csharp
  Mvx.IoCProvider.RegisterType();
  

- LazyConstructAndRegisterSingleton: Similar to `RegisterSingleton`, but the instance is created lazily, only when first resolved.

csharp
  Mvx.IoCProvider.LazyConstructAndRegisterSingleton();
  

Open-Generic Registration

If you have generic interfaces, you need to register them explicitly for each type parameter:

csharp
Mvx.IoCProvider.RegisterType, Foo>();
Mvx.IoCProvider.RegisterType, Foo>();

Resolving Registered Objects

Once objects are registered, they can be resolved using the IoC container. For example, if you have a `ViewModel` that depends on a service, MvvmCross will automatically inject the registered service instance into the `ViewModel` constructor:

csharp
public MyViewModel(IMyService myService)
{
    MyService = myService;
}

In this case, `IMyService` must be registered in the IoC container for MvvmCross to resolve it correctly.

Customizing the IoC Provider

If needed, you can override the default IoC provider in the `Setup` class to use a custom provider:

csharp
public override IMvxIoCProvider CreateIocProvider()
{
    return new MyCustomIoCProvider();
}

This allows for more flexibility in managing dependencies across your application.

In summary, MvvmCross simplifies the registration of custom objects using its IoC container, providing both automated and manual registration methods to suit different needs.