Disable close button and miniaturize window in MAUI MacCatalyst application

Question

I have a MAUI app (exclusively for MacCatalyst). I need to work with a C# library so I cannot rewrite it in Xcode.

I want to gray out the close button and miniaturise the window at app launch. I know how to achieve it inside a C# Cocoa app, but not in a MAUI MacCatalyst app. This code is the code that works well for the Cocoa app :

NSWindow window = NSApplication.SharedApplication.MainWindow;
NSButton button = window.StandardWindowButton(NSWindowButton.CloseButton);
button.Hidden = true;
window.SetIsMiniaturized(true);

I want to achieve the same thing in my MAUI MacCatalyst app.

I know it is possible to miniaturise and disable the close button in Swift like this for example:

guard let nsWindows = NSClassFromString("NSApplication")?.value(forKeyPath: "sharedApplication.windows") as? [AnyObject] else { return }
for nsWindow in nsWindows {
 nsWindow.setIsMiniaturized(true)
 nsWindow.standardWindowButton(.closeButton).setEnabled(false);
 }

But I cannot find a way to do it in the MAUI project, as NSClassFromString is unknown from MAUI.

I have tried to do it in a native swift framework (distributed as MacWindowManager.xcframework), that I can call through a native binding library. But there seem to be a limitation somewhere, as the native binding works fine when I try it with a simple function like this

@objc public func TestAdd(i:Int, y:Int)-> Int{
        return i + y;
    }

However when I introduce a function regarding a code like this

guard let nsWindows = NSClassFromString("NSApplication")?.value(forKeyPath: "sharedApplication.windows") as? [AnyObject] else { return }

everything compiles but the MAUI MacCatalyst app is not launched.

I tried using the package Dynamic in the native library, but no luck either

@objc public func SetUpWindow(uiWindow:UIWindow){
   let window = Dynamic.NSApplication.sharedApplication.delegate.hostWindowForUIWindow(uiWindow)
   let button = Dynamic(window).standardWindowButton(Dynamic.NSWindow.ButtonType.closeButton)
   Dynamic(button).setEnabled(false)
   Dynamic(window).setIsMiniaturized(true)
}

I have seen the possibility of creating a MacOS bundle like in this article about Disabling the Mac Zoom/Maximise Button in Catalyst. The thing is I don't know how to embed a MacOS bundle into a .xcframework.

Has anyone succeeded in calling AppKit functionalities from a swift framework, linked through a native binding project to a MAUI MacCatalyst application ?

Or do you have any idea regarding why it is not working ?

Or do you know a way to achieve this directly with MAUI ?

This post for example shows how to disable the maximize/minimise button, but I cannot make it work for Maui.

Thanks!

Answer 1

You can use the handler to control the windows. Here is the sample to change the size of the window in MacCatalyst.

Microsoft.Maui.Handlers.WindowHandler.Mapper.AppendToMapping(
        nameof(IWindow), (handler, view) =>
        {
            var size = new CoreGraphics.CGSize(width, height);
            handler.PlatformView.WindowScene.SizeRestrictions.MinimumSize = size;
            handler.PlatformView.WindowScene.SizeRestrictions.MaximumSize = size;
            Task.Run(() =>
            {
                Thread.Sleep(1000);
                MainThread.BeginInvokeOnMainThread(() =>
                {
                    handler.PlatformView.WindowScene.SizeRestrictions.MinimumSize = new CoreGraphics.CGSize(100, 100);
                    handler.PlatformView.WindowScene.SizeRestrictions.MaximumSize = new CoreGraphics.CGSize(5000, 5000);
                });
            });

        });