References a method to be called when a corresponding asynchronous operation completes.
Assembly: mscorlib (in mscorlib.dll)
Use an delegate to process the results of an asynchronous operation in a separate thread. The delegate represents a callback method that is called when the asynchronous operation completes. The callback method takes an IAsyncResult parameter, which is subsequently used to obtain the results of the asynchronous operation.
For more information about asynchronous programming, see Using an AsyncCallback Delegate to End an Asynchronous Operation and Using an AsyncCallback Delegate and State Object in Event-based Asynchronous Pattern (EAP).
The following code example demonstrates using asynchronous methods in the Dns class to retrieve Domain Name System (DNS) information for user-specified computers. This example creates an delegate that references the ProcessDnsInformation method. This method is called once for each asynchronous request for DNS information.
.NET FrameworkSupported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0
.NET Framework Client ProfileSupported in: 4, 3.5 SP1
Portable Class LibrarySupported in: Portable Class Library
.NET for Windows Store appsSupported in: Windows 8
.NET for Windows Phone appsSupported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1
Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.