Demo registers Progress handler from IAsyncOperationWithProgress

MainPage.xaml.cpp

void WebCrawlerSample::MainPage::button_Click(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e)
{
	HttpClient^ client = ref new HttpClient();
	Uri^ addr = ref new Uri("https://heejune.me");

	auto asyncOp = client->GetAsync(addr);

	// create and set Progress handler
	asyncOp->Progress = ref new AsyncOperationProgressHandler<HttpResponseMessage^, HttpProgress>(
		[=](IAsyncOperationWithProgress<HttpResponseMessage^, HttpProgress>^ pretask, HttpProgress progressInfo) {

		// access ui element
		Windows::ApplicationModel::Core::CoreApplication::MainView->CoreWindow->Dispatcher->RunAsync(
			CoreDispatcherPriority::Normal,
			ref new Windows::UI::Core::DispatchedHandler([this, progressInfo]() {
			textBlock->Text += progressInfo.BytesReceived.ToString() + "\n";
		}));
	});

	auto task = create_task(asyncOp);

	// get result
	task.then([=](HttpResponseMessage ^ msg) {
		// access ui element
		Windows::ApplicationModel::Core::CoreApplication::MainView->CoreWindow->Dispatcher->RunAsync(
			CoreDispatcherPriority::Normal,
			ref new Windows::UI::Core::DispatchedHandler([this, msg]() {
			textBlock->Text += msg->StatusCode.ToString();
		}));

	});
}