Hands-On Parallel Programming with C# 8 and .NET Core 3

Using the IAsyncResult interface

The IAsyncResult interface has been used to implement asynchronous programming in older versions of C#. The following is some example code that works well in earlier versions of .NET:

1. First, we create AsyncCallback that will be executed when the async method finishes:

AsyncCallback callback = new AsyncCallback(MyCallback);

2. Then, we create a delegate that will execute an Add method with the parameters that are passed. Once finished, it will execute the callback method wrapped by AsyncCallBack:

SumDelegate d = new SumDelegate(Add);d.BeginInvoke(100, 200, callback, state);

3. When the MyCallBack method is called, it returns the IAsyncResult instance. To get the underlying result, state, and callback, we need ...