FromAsync Method (IAsyncResult, Action(IAsyncResult), TaskCreationOptions)
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TaskFactory.FromAsync Method (IAsyncResult, Action<IAsyncResult>, TaskCreationOptions)


Creates a Task that executes an end method action when a specified IAsyncResult completes.

Namespace:   System.Threading.Tasks
Assembly:  mscorlib (in mscorlib.dll)

public Task FromAsync(
	IAsyncResult asyncResult,
	Action<IAsyncResult> endMethod,
	TaskCreationOptions creationOptions


Type: System.IAsyncResult

The IAsyncResult whose completion should trigger the processing of the endMethod.

Type: System.Action<IAsyncResult>

The action delegate that processes the completed asyncResult.

Type: System.Threading.Tasks.TaskCreationOptions

The TaskCreationOptions value that controls the behavior of the created Task.

Return Value

Type: System.Threading.Tasks.Task

A Task that represents the asynchronous operation.

Exception Condition

The exception that is thrown when the asyncResult argument is null.


The exception that is thrown when the endMethod argument is null.


The exception that is thrown when the creationOptions argument specifies an invalid TaskCreationOptions value. For more information, see the Remarks for FromAsync


The FromAsync overloads that take an asyncResult parameter are not as efficient as the overloads that take a beginMethod parameter. If performance is an issue, use the overloads that provide the beginMethod/endMethod pattern.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Available since 5.0
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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