UWP C++ ContentDialog PrimaryButtonCommand or PrimaryButtonClick

I'm trying to use ContentDialog^ in a UWP C++ app. With MessageDialog^ you can easily set the buttons and commands Windows::UI::Popups::UICommand they invoke when touched

MessageDialog^ msg = ref new MessageDialog("Data changed - Save?");
msg->Title = "Warning";

// Add commands and set their callbacks.
UICommand^ continueCommand = ref new UICommand("Yes", ref new UICommandInvokedHandler(this, &MainPage::CommandInvokedHandler));
UICommand^ upgradeCommand = ref new UICommand("No", ref new UICommandInvokedHandler(this, &MainPage::CommandInvokedHandler));
UICommand^ cancelCommand = ref new UICommand("Cancel", ref new UICommandInvokedHandler(this, &MainPage::CommandInvokedHandler));

then you can easily access the value sent to the CommandInvokedHandler by

void MainPage::CommandInvokedHandler(Windows::UI::Popups::IUICommand^ command)
{
    // Display message
    if (command->Label == "Yes") {
        Save();
    } else if (command->Label == "No") {
        Skip();
    } else if (command->Label == "Cancel") {
        //do nothing
    }
}

However, the content dialog works completely differently. It's created like this

TextBox^ inputTextBox = ref new TextBox();
inputTextBox->AcceptsReturn = false;
inputTextBox->Height = 32;
ContentDialog^ dialog = ref new ContentDialog();

dialog->Content = inputTextBox;
dialog->Title = "Rename";
dialog->IsSecondaryButtonEnabled = true;
dialog->PrimaryButtonText = "Ok";
dialog->SecondaryButtonText = "Cancel";
dialog->ShowAsync();

I either need to set the property dialog->PrimaryButtonCommand that for some (unknown bizarre) reason uses the completely different Windows::UI::Xaml::Input::ICommand...
Or should I use the dialog->PrimaryButtonClick?

I'm struggling to find any C++ examples anywhere and the documentation doesn't clear anything up.