CoreDispatcher.RunAsync method

Applies to Windows and Windows Phone

Schedules the provided callback on the UI thread from a worker thread, and returns the results asynchronously.


public IAsyncAction RunAsync(
  CoreDispatcherPriority priority, 
  DispatchedHandler agileCallback



Type: CoreDispatcherPriority

Specifies the priority for event dispatch. Set this to CoreDispatcherPriority::Normal.


Type: DispatchedHandler

The callback on which the dispatcher returns when the event is dispatched.

Return value

Type: IAsyncAction

The object that provides handlers for the completed async event dispatch.


If you are on a worker thread and want to schedule work on the UI thread, use CoreDispatcher::RunAsync. Always set the priority to CoreDispatcherPriority::Normal or CoreDispatcherPriority::Low, and ensure that any chained callbacks also use CoreDispatcherPriority::Normal or CoreDispatcherPriority::Low.

If you are porting from the Microsoft .NET Framework Dispatcher.BeginInvoke and Dispatcher.Invoke methods, note that CoreDispatcher::RunAsync is asynchronous. There is no synchronous version. After you change Dispatcher.Invoke to CoreDispatcher::RunAsync, your code must support the Windows Runtime async pattern and use the specific lambda syntax for your chosen language.

The following examples demonstrate the use of CoreDispatcher::RunAsync to schedule work on the main UI thread using the CoreWindow's event dispatcher.

To spin off a worker thread from the UI thread, do not use this method (CoreDispatcher::RunAsync). Instead, use one of the Windows::System::Threading::ThreadPool::RunAsync method overloads.

Note  Callbacks scheduled with CoreDispatcherPriority::Low priority are called when there are no pending input events. Use the CoreDispatcherPriority::Low priority to make your app UI more responsive. To schedule background tasks, use CoreDispatcher::RunIdleAsync.

await dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
   rootPage.NotifyUser("The toast encountered an error", NotifyType.ErrorMessage);

var ignored = dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
   Scenario3OutputText.Text += outputText;


Minimum supported client

Windows 8

Minimum supported server

Windows Server 2012

Minimum supported phone

Windows Phone 8


Windows::UI::Core [C++]



See also




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