CoreDispatcher.RunAsync Method
Schedules the provided callback on the UI thread from a worker thread, and returns the results asynchronously.
Syntax
public:
IAsyncAction^ RunAsync(
CoreDispatcherPriority priority,
DispatchedHandler^ agileCallback
)
Parameters
priority
Type: CoreDispatcherPriority
Specifies the priority for event dispatch. Set this to CoreDispatcherPriority::Normal.
agileCallback
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.
Remarks
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 FrameworkDispatcher.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.
Work scheduled with CoreDispatcher::RunAsync will execute on the thread where the CoreWindow event dispatcher is processed.
Example
C++
//
_dispatcher->RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal,
ref new Windows::UI::Core::DispatchedHandler([this]()
{
_count++;
TimerTextBlock->Text = "Total Running Time: " + _count.ToString() + " Seconds";
}));
// using CallbackContext::Any
void Playback::DisplayStatus(Platform::String^ text)
{
_dispatcher->RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal,
ref new Windows::UI::Core::DispatchedHandler([=]()
{
_OutputStatus->Text += text + "\n";
}, CallbackContext::Any));
}
Example
Requirements
Namespace: Windows.UI.Core
Metadata: windows.winmd