donet/Wpf/Prism1/ModuleA/Views/ViewC.xaml.cs

using System.Windows;
using System.Windows.Controls;
using ModuleA.Event;
using Prism.Events;

namespace ModuleA.Views;

public partial class ViewC : UserControl
{
    public ViewC(IEventAggregator aggregator)
    {
        InitializeComponent();
        var messageEvent = aggregator.GetEvent<MessageEvent>();
        messageEvent.Subscribe(arg =>
        {
            MessageBox.Show(arg);
        });
    }
}