This documentation is archived and is not being maintained.

Dispatcher.Invoke Method (Delegate, TimeSpan, Object())

Updated: July 2008

Executes the specified delegate within the designated time span at the specified priority with the specified arguments synchronously on the thread the Dispatcher is associated with.

Namespace:  System.Windows.Threading
Assembly:  WindowsBase (in WindowsBase.dll)

Public Function Invoke ( _
	method As Delegate, _
	timeout As TimeSpan, _
	ParamArray args As Object() _
) As Object
Dim instance As Dispatcher 
Dim method As [Delegate]
Dim timeout As TimeSpan 
Dim args As Object()
Dim returnValue As Object 

returnValue = instance.Invoke(method, _
	timeout, args)
You cannot use methods in XAML.


Type: System.Delegate

A delegate to a method that takes parameters specified in args, which is pushed onto the Dispatcher event queue.

Type: System.TimeSpan

The maximum amount of time to wait for the operation to complete.

Type: System.Object()

An array of objects to pass as arguments to the given method. Can be Nothing.

Return Value

Type: System.Object
The return value from the delegate being invoked or Nothing if the delegate has no return value.

In WPF, only the thread that created a DispatcherObject may access that object. For example, a background thread that is spun off from the main UI thread cannot update the contents of a Button that was created on the UI thread. In order for the background thread to access the Content property of the Button, the background thread must delegate the work to the Dispatcher associated with the UI thread. This is accomplished by using either Invoke or BeginInvoke. Invoke is synchronous and BeginInvoke is asynchronous. The operation is added to the event queue of the Dispatcher at the specified DispatcherPriority.

Invoke is a synchronous operation; therefore, control will not return to the calling object until after the callback returns.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5 SP1, 3.0 SP2




July 2008

Added topic for new member.

SP1 feature change.