从ViewModel到View Xamarin的MVVMCross调用函数

Question

I want to show a popup when someone click on a button, the button is in a listview which is load from a webservice, how can I send a message to the view to call the AlertDialog function ?

I was maybe not very clear I paste my code bellow to see what I tried :

In my viewmodel :

public void editPost(Post item)
{
    PostToEdit = item;

    // Call the popup function
}

In my view :

public Dialog showEditPopup()
{
    var customView = LayoutInflater.Inflate(Resource.Layout.EditDialog, null);

    var builder = new AlertDialog.Builder(this);
    builder.SetView(customView);
    builder.SetPositiveButton("Save", SaveClicked);
    builder.SetNegativeButton("Cancel", CancelClicked);

    return builder.Create();  
}

I tried to create an onclick function to initialize my AlertDialog in the View

var editButton = FindViewById<Button>(Resource.Id.editButton);
editButton.Click += delegate { ShowDialog(EditDialog); }; 

But the application crash because the posts aren't load at the time of the oncreate so the editButton is null and the event click cannot be set, so I want to create the popup in the viewmodel.

Answer 1

One way you can go about this is to set (from the view) an Action or Func callback on the VM, which will show the dialog, and it can be initiated from the VM.
The other option would be to have an interface defined by the VM which the View will implement (for example IViewInteraction which has a method like ShowDialog(string text) .

I would suggest the first approach.

Answer 2

Probably there's going to be more than one place where you will need to show an alert dialog in your app.

In MvvmCross there's a plugin to show dialogs in all platforms. You implement calling it from view-model and it will work on all platforms.

https://github.com/brianchance/MvvmCross-UserInteraction

I suggest you add it by NuGet