Render datalayer from another c# class like refresh ()

Question

How to make my Mapsui layers visible and rendered after I call the below void function from another class? MyMap.Refesh() does so I don’t get a null error?

In my code behind MapsuiControl.xaml.cs file I have:

public void CreateImageLayer()
{
            MyMap.Map.Layers.Add(_imageLayerFactoryTwo.CreateLayer());
            MyMap.Refresh();
 }

In the xaml file MapsuiControl.xaml I have:

<winui:MapControl x:Name="MyMap" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" />

The another c# class call the code-behind file in this function:

private void SendImageLayerString()
    {
     
        mapsuiControl.CreateImageLayer();
       
    }

I can only show the layer when I using this code in the constructor at the code-behind file MapsuiControl.xaml.cs but I want it in a void function that is called from another c# class: MyMap.Map.Layers.Add(_imageLayerFactoryTwo.CreateLayer());

The whole constructor when I can show the datalayer is:

public MapsuiControl()
        {
            this.InitializeComponent();        
            MyMap.Map.Layers.Add(OpenStreetMap.CreateTileLayer());
            MyMap.Map.Layers.Add(_imageLayerFactory.CreateLayer());
        }

The c# class I want to call it from:

public class UserSenderViewModel : ObservableRecipient
    {
        
        private MapsuiControl mapControl; /*= new ();*/

        public UserSenderViewModel()
        {
            mapControl = new MapsuiControl();
        }
        public void SendUserMessage()
        {
        
            mapControl.CreateImageLayer();
        }

Another example:

I had also tried to create a MapsuiControl from the beginning like MainViewModel.cs => UserSenderViewModel

public partial class MainViewModel : ObservableObject
{
    
    private MapsuiControl _mapsuiControl; 


    private UserSenderViewModel _userSenderViewModel;
    

    public MainViewModel()
    {
        _mapsuiControl = new MapsuiControl();
        _userSenderViewModel = new UserSenderViewModel(_mapsuiControl);
        
    }

    public UserSenderViewModel UserSenderViewModel { get { return _userSenderViewModel; } }

and UserSenderViewModel.cs:

public class UserSenderViewModel : ObservableRecipient
    {
        
        private MapsuiControl _mapControl;

        public UserSenderViewModel(MapsuiControl mapControl)
        {
            _mapControl = mapControl;
        }
        public void SendUserMessage()
        {
            
            _mapControl.CreateImageLayer();
            
        }

With ICommand:

MainViewModel.cs:

public ICommand SendImageLayerCommand { get; }

    private string imageLayer = "Image Layer";

    public string ImageLayer
    {
        get => imageLayer;
        private set => SetProperty(ref imageLayer, value);
    }

    private void SendImageLayerString()
    {
        
        
        _mapsuiControl.CreateImageLayer();
        
    }

Xaml file in a usercontrol:

<Button 
            Content="Show Image Datalayer"
            Command="{x:Bind ViewModel.SendImageLayerCommand, Mode=OneWay}"
            />