Uno Support for Windows.UI.Core.Preview


The CloseRequested event is supported on macOS. No additional capability needs to be declared in the application manifest as opposed to UWP which requires the confirmAppClose capability.

To execute asynchronous logic, get a deferral at the beginning of the event handler and complete it after the logic is finished.

Example of a close confirmation dialog:

private async void App_CloseRequested(object sender, SystemNavigationCloseRequestedPreviewEventArgs e)
    var deferral = e.GetDeferral();
    var dialog = new MessageDialog("Are you sure you want to exit?", "Exit");
    var confirmCommand = new UICommand("Yes");
    var cancelCommand = new UICommand("No");
    if (await dialog.ShowAsync() == cancelCommand)
        //cancel close by handling the event
        e.Handled = true;