如何基于MvxViewModelRequest为UWP创建视图？

Hey there! Let's tackle this problem you're facing with MvvmCross in UWP. I’ve worked with exactly these versions of MvvmCross and UWP before, so here’s a practical solution to replicate that WPF-style view creation behavior:

Unlike WPF, UWP doesn’t have a built-in IMvxSimpleWpfViewLoader, but we can build a equivalent by leveraging MvvmCross’s core view-model mapping and view loading systems. Here’s step-by-step how to do it:

1. Create a Custom View Loader Interface and Implementation #

First, we’ll make a reusable loader that mimics the WPF behavior, returning a FrameworkElement (which all UWP views inherit from):

public interface IMvxSimpleUwpViewLoader
{
    FrameworkElement CreateView(MvxViewModelRequest request);
}

public class MvxSimpleUwpViewLoader : IMvxSimpleUwpViewLoader
{
    public FrameworkElement CreateView(MvxViewModelRequest request)
    {
        // Step 1: Get the corresponding view type for the view model
        var viewsContainer = Mvx.Resolve<IMvxViewsContainer>();
        var viewType = viewsContainer.GetViewType(request.ViewModelType);
        
        if (viewType == null)
            throw new MvxException($"No matching view found for {request.ViewModelType.Name}");

        // Step 2: Instantiate the view
        var view = Activator.CreateInstance(viewType) as FrameworkElement;
        if (view == null)
            throw new MvxException($"Failed to create instance of view type {viewType.Name}");

        // Step 3: Load the view model and link it to the view
        var viewModelLoader = Mvx.Resolve<IMvxViewModelLoader>();
        var viewModel = viewModelLoader.LoadViewModel(request, null);

        // Use MvvmCross's built-in view interface if available (most UWP views inherit from MvxWindowsPage/UserControl)
        if (view is IMvxWindowsView mvxView)
        {
            mvxView.ViewModel = viewModel;
        }
        else
        {
            // Fallback to setting DataContext directly for custom views
            view.DataContext = viewModel;
        }

        return view;
    }
}

2. Register the Loader in Your Setup Class #

Open your Setup.cs file (usually in your UWP project) and register the loader in the final initialization step:

protected override void InitializeLastChance()
{
    base.InitializeLastChance();
    Mvx.RegisterSingleton<IMvxSimpleUwpViewLoader>(new MvxSimpleUwpViewLoader());
}

3. Use It Just Like the WPF Implementation #

Now you can call it exactly the way you did in WPF:

var request = new MvxViewModelRequest(
    viewModelType, 
    parameterBundle, 
    presentationBundle, 
    null);

var view = Mvx.Resolve<IMvxSimpleUwpViewLoader>().CreateView(request);

// Add the view to your UWP page/container as needed
// Example: MyGrid.Children.Add(view);

Key Notes for Your Environment #

• Naming Conventions: Make sure your view and view model follow MvvmCross’s default naming rules (e.g., HomeViewModel maps to HomePage or HomeView). If you need custom mappings, override GetViewType in your Setup class or use the [MvxViewModel(typeof(YourViewType))] attribute on your view model.
• ViewModel Initialization: Any parameters in parameterBundle will automatically be passed to your view model’s Initialize method (if it implements IMvxViewModel<TParameter> or IMvxAsyncViewModel).
• Lifecycle: If your view inherits from MvxWindowsPage or MvxWindowsUserControl, MvvmCross will handle lifecycle events like ViewAppearing and ViewDisappearing automatically once the view is added to the visual tree.

内容的提问来源于stack exchange，提问作者mazury