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

Creates a Task that represents a pair of begin and end methods that conform to the Asynchronous Programming Model pattern.

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

public Task FromAsync(
	Func<AsyncCallback, Object, IAsyncResult> beginMethod,
	Action<IAsyncResult> endMethod,
	Object state,
	TaskCreationOptions creationOptions


Type: System.Func<AsyncCallback, Object, IAsyncResult>

The delegate that begins the asynchronous operation.

Type: System.Action<IAsyncResult>

The delegate that ends the asynchronous operation.

Type: System.Object

An object containing data to be used by the beginMethod delegate.

Type: System.Threading.Tasks.TaskCreationOptions

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

Return Value

Type: System.Threading.Tasks.Task
The created Task that represents the asynchronous operation.


The exception that is thrown when the beginMethod 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.

The beginMethod delegate is started on the thread that FromAsync is running on. This method throws any exceptions thrown by the beginMethod. The TaskCreationOptions values PreferFairness, LongRunning and AttachedToParent are all mutually exclusive. In the FromAsync methods, either LongRunning or AttachedToParent by themselves will cause an ArgumentOutOfRangeException to be thrown.

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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