DSoft.System.Mvvm.UI.Forms 3.1.2205.231

System.Mvvm.UI.Forms

Provides Xamarin.Forms platform implementations for DSoft.System.Mvvm.UI

Functionality

• UI
  • Core UI functions for Showing Alerts and Confirmation Dialogs
  • UI Thread execution
  • Dependency injection support with IPlatformCoreUIProvider

Using System.Mvvm.UI.Forms

The UI static class provides four methods as defined in the IPlatformCoreUIProvider interface.

• A central interface for calling some simple UI functions
  • ShowAlert(string title, string message)
    • Show an alert with a title and message using the platform implementation
  • ShowConfirmation(string title, string message)
    • Show a confirmation dialog and return the result using the platform implementation
  • InvokeOnUIThread(Action)
    • Execute the action on the UI thread using the platform implementation
  • InvokeOnUIThreadAsync(Action)
    • Execute the action on the UI thread asyncronously using the platform implementation

The standard UI functions can be called directly after adding the DSoft.Mvvm.UI package to your shared code

using System.Mvvm;
... 

var result = await UI.ShowConfirmationDialogAsync("Confirm this", "This is a platform specific confirmation message");

if (result)
    await UI.ShowAlertAsync("YAY!", "You confirmed that");

In the shared Xamarin.Forms project that contains the App class(or other sub-class of Application), add the DSoft.System.Mvvm.UI.Forms package.

Note: do not add System.Mvvm.UI.Forms directly to the mobile application for iOS, Android or UWP

Call the MvvmManager.Init method in the shared code, such as Application.OnStart

using System.Mvvm;
... 
public partial class App : Application
{
    protected override OnStart()
    {
        base.OnStart();

        MvvmManager.Init();
    }
}

Dependency Injection

Instead of using the static UI class you can use dependency injection to access the platform implementation of IPlatformCoreUIProvider using extensions for IServiceCollection provided by the platform specific packages.

After adding DSoft.System.Mvvm.UI.Forms to the application project you can register the core UI implementations of IPlatformCoreUIProvider with the ServiceProvider during configuration of the services using the AddCoreUI extension method.

using System.Mvvm;
... 
public partial class App : Application
{
    public App()
    {
        InitializeComponent();

        ServiceHost.Host = new HostBuilder()
         .ConfigureHostConfiguration(c =>
         {
             c.AddCommandLine(new string[] { $"ContentRoot={FileSystem.AppDataDirectory}" });
         })
         .ConfigureServices(ConfigureServices)
         .Build();
    }

    void ConfigureServices(HostBuilderContext ctx, IServiceCollection services)
    {
       services.AddCoreUI();
    }
}

Once the core UI is registered you can use IPlatformCoreUIProvider with dependency injection in class constructors.

using System.Mvvm;
... 
public class SharedClassToDoThingsIn
{
   private readonly IPlatformCoreUIProvider _coreUIProvider;

    public SharedClassToDoThingsIn(IPlatformCoreUIProvider coreUIProvider)
    {
        _coreUIProvider = coreUIProvider;
    }

    public async Task SayHello()
    {
        await _coreUIProvider.ShowAlertAsync("Congrats", "You called the ICoreUIProvider instance");
    }
}

Use can also retrieve the implementation directly from the services provider or ServiceHost if you are using DSoft.System.Mvvm.Hosting

using System.Mvvm;
... 

var _coreUIProvider = ServiceHost.GetRequiredService<IPlatformCoreUIProvider>();

await _coreUIProvider.ShowAlertAsync("Congrats", "You called the ICoreUIProvider instance");

Using DI instead of the UI does not require a call to MvvmManager.Init though you do have to call the extension method to register the services. You can also use both.

IXamarinFormsPlatformUIProvider

IXamarinFormsPlatformUIProvider is a platform specific interface that the platform implementation of `` implements. It provides access to some additonal Xamarin.Forms properties such as the current Application.

Use can retrieve the implementation directly from the services provider or ServiceHost if you are using DSoft.System.Mvvm.Hosting

using System.Mvvm;
... 

var _formsUIProvider = ServiceHost.GetRequiredService<IXamarinFormsPlatformUIProvider>();

var currentApp = _formsUIProvider.CurrentApplication;