How to disabled fullscreen button on MacCatalyst

Question

Currently, I have this to stop resizing window:

#if targetEnvironment(macCatalyst)
windowScene.sizeRestrictions?.minimumSize = CGSize(width: 480, height: 900)
windowScene.sizeRestrictions?.maximumSize = CGSize(width: 480, height: 900)
#endif

let window = UIWindow(windowScene: windowScene)
window.rootViewController = UIHostingController(rootView: contentView)
self.window = window
window.makeKeyAndVisible()

but the fullscreen button makes it full screen anyway.

Answer 1

Here is another approach that does not need Objective-C, selectors, or asynchronous calls. It also does not need target macros, iOS will simply skip if let NSApplication. Paste it into your view controller that appears first. Note that this disables the green full-screen button on all your windows. If you want to differentiate, use ideas from Asperi's Swift part.

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)

    func bitSet(_ bits: [Int]) -> UInt {
        return bits.reduce(0) { $0 | (1 << $1) }
    }

    func property(_ property: String, object: NSObject, set: [Int], clear: [Int]) {
        if let value = object.value(forKey: property) as? UInt {
            object.setValue((value & ~bitSet(clear)) | bitSet(set), forKey: property)
        }
    }

    // disable full-screen button
    if  let NSApplication = NSClassFromString("NSApplication") as? NSObject.Type,
        let sharedApplication = NSApplication.value(forKeyPath: "sharedApplication") as? NSObject,
        let windows = sharedApplication.value(forKeyPath: "windows") as? [NSObject]
    {
        for window in windows {
            let resizable = 3
            property("styleMask", object: window, set: [], clear: [resizable])
            let fullScreenPrimary = 7
            let fullScreenAuxiliary = 8
            let fullScreenNone = 9
            property("collectionBehavior", object: window, set: [fullScreenNone], clear: [fullScreenPrimary, fullScreenAuxiliary])
        }
    }
}