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AsyncCompletedEventHandler Delegate

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Represents the method that will handle the MethodNameCompleted event of an asynchronous operation.

Namespace:  System.ComponentModel
Assembly:  System (in System.dll)

Syntax

'Declaration
Public Delegate Sub AsyncCompletedEventHandler ( _
    sender As Object, _
    e As AsyncCompletedEventArgs _
)

public delegate void AsyncCompletedEventHandler(
    Object sender,
    AsyncCompletedEventArgs e
)

Parameters

Remarks

When you create an AsyncCompletedEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event-handler method is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events Overview for Silverlight.

For an asynchronous method, which is named MethodName, in your component, you will have a corresponding MethodNameCompleted event, and an optional MethodNameCompletedEventArgs class.

For a component that supports multiple concurrent invocations of its asynchronous methods, the client can supply a unique token, or task ID, to distinguish which asynchronous task is raising particular events. The client's AsyncCompletedEventHandler can read the AsyncCompletedEventArgs.UserState property to determine which task is reporting completion. Your implementation should use the System.ComponentModel.AsyncOperationManager to create an System.ComponentModel.AsyncOperation that associates the client's task IDs with pending asynchronous tasks.

Examples

For a code example of the AsyncCompletedEventHandler delegate, see the example in the System.ComponentModel.AsyncCompletedEventArgs class.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.