Event must be of delegate type?

Question

Not very familiar with declaring and using events and received error,

Event must be of delegate type

Basically want to pass IMyInterface as a dependency to another class where that class can subscribe to receive MyClassEvent events and the event data is MyClass.

public interface IMyInterface
{
   event MyClass MyClassEvent;
}

public class Implementation: IMyInterface
{
     event MyClass MyClassEvent;
     public void OnSomethingHappened
     {
         MyClassEvent?.Invoke(); // pass MyClass to subscribers
     }
}

public class AnotherClass(IMyInterface ...)
{
    OnMyClassEvent(MyClass args)
    {
       // do something
    }
}

Answer 1

You need to declare the event correctly and define the event args:

public class MyClassEventArgs : EventArgs { }

public interface IMyInterface
{
    event EventHandler<MyClassEventArgs> MyClassEvent;
}

public class Implementation : IMyInterface
{
    public event EventHandler<MyClassEventArgs> MyClassEvent;

    public void OnSomethingHappened()
    {
        MyClassEvent?.Invoke(this, new MyClassEventArgs());
    }
}

And to subscribe to it:

var implementation = new Implementation();
implementation.MyClassEvent += MyClassEvent;

private void MyClassEvent(object sender, MyClassEventArgs e) { ... }