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DispatcherHelper

  • Article

Warning

This type has been deprecated and it will be removed from the Windows Community Toolkit, please refer to the DispatcherQueueExtensions type.

The DispatcherHelper class enables easy interaction with CoreDispatcher, mainly in the case of executing a block of code on the UI thread from a non-UI thread.

What is included in the helper?

  • Extension method with overloads for CoreDispatcher class.

  • Extension method with overloads for CoreApplicationView (for multi window applications).

  • Static helper methods for executing a specific function on the UI thread of the current application's main window.

Try it in the sample app

Syntax

DispatcherHelper.ExecuteOnUIThreadAsync<T>(() =>
{
    // Code to execute on main window's UI thread
});

await CoreApplication.MainView.Dispatcher.AwaitableRunAsync<T>( () =>
{
    
});

DispatcherHelper.ExecuteOnUIThreadAsync(Of T)(Function()
    ' Code to execute on main window's UI thread
End Function)

Await CoreApplication.MainView.Dispatcher.AwaitableRunAsync(Of T)(Function()

End Function)

Methods

Methods Return Type Description
AwaitableRunAsync(CoreDispatcher, Action, CoreDispatcherPriority) Task Extension method for CoreDispatcher. Offering an actual awaitable Task with optional result that will be executed on the given dispatcher
AwaitableRunAsync(CoreDispatcher, Func, CoreDispatcherPriority) Task Extension method for CoreDispatcher. Offering an actual awaitable Task with optional result that will be executed on the given dispatcher
AwaitableRunAsync(CoreDispatcher, Func<Task<T>>, CoreDispatcherPriority) Task<T> Extension method for CoreDispatcher. Offering an actual awaitable Task with optional result that will be executed on the given dispatcher
AwaitableRunAsync(CoreDispatcher, Func, CoreDispatcherPriority) Task<T> Extension method for CoreDispatcher. Offering an actual awaitable Task with optional result that will be executed on the given dispatcher
ExecuteOnUIThreadAsync(Action, CoreDispatcherPriority) Task Execute the given function asynchronously on given view's UI thread. Default view is the main view
ExecuteOnUIThreadAsync(Func, CoreDispatcherPriority) Task Execute the given function asynchronously on UI thread of the main view
ExecuteOnUIThreadAsync(CoreApplicationView, Action, CoreDispatcherPriority) Task Execute the given function asynchronously on given view's UI thread. Default view is the main view
ExecuteOnUIThreadAsync(CoreApplicationView, Func, CoreDispatcherPriority) Task Execute the given function asynchronously on given view's UI thread. Default view is the main view
ExecuteOnUIThreadAsync(Func<Task<T>>, CoreDispatcherPriority) Task<T> Execute the given function asynchronously on UI thread of the main view
ExecuteOnUIThreadAsync(Func<T>, CoreDispatcherPriority) Task<T> Execute the given function asynchronously on given view's UI thread. Default view is the main view
ExecuteOnUIThreadAsync(CoreApplicationView, Func<Task<T>>, CoreDispatcherPriority) Task<T> Execute the given function asynchronously on given view's UI thread. Default view is the main view
ExecuteOnUIThreadAsync(CoreApplicationView, Func, CoreDispatcherPriority) Task<T> Execute the given function asynchronously on given view's UI thread. Default view is the main view

Example

// Executing from a non-UI thread with helper method
int returnedFromUIThread = await DispatcherHelper.ExecuteOnUIThreadAsync<int>(() =>
{
    // Code to execute on main window's UI thread
    NormalTextBlock.Text = "Updated from a random thread!";
    return 1;
});

// returnedFromUIThread now is 1, execution can go on from the non-UI thread

// Or update it manually via the Extension method for CoreDispatcher
returnedFromUIThread = await CoreApplication.MainView.Dispatcher.AwaitableRunAsync<int>(() =>
{
    NormalTextBlock.Text = "Updated from a random thread with extension method!";
    return 1;
});

' Executing from a non-UI thread with helper method
Dim returnedFromUIThread As Integer = Await DispatcherHelper.ExecuteOnUIThreadAsync(Of Integer)(Function()
    ' Code to execute on main window's UI thread
    NormalTextBlock.Text = "Updated from a random thread!"
    Return 1
End Function)

' returnedFromUIThread now is 1, execution can go on from the non-UI thread

' Or update it manually via the Extension method for CoreDispatcher
returnedFromUIThread = Await CoreApplication.MainView.Dispatcher.AwaitableRunAsync(Of Integer)(Function()
    NormalTextBlock.Text = "Updated from a random thread with extension method!"
    Return 1
End Function)

Sample Project

DispatcherHelper Sample Page Source. You can see this in action in the Windows Community Toolkit Sample App.

Requirements

Device family Universal, 10.0.16299.0 or higher
Namespace Microsoft.Toolkit.Uwp

API