Creating a transparent window in SwiftUI

HiddenTitlebar.swift

// requires Introspect package: https://github.com/siteline/SwiftUI-Introspect

extension View {
    private func introspectView(customize: @escaping (NSView) -> ()) -> some View {
        return inject(AppKitIntrospectionView(
            selector: { introspectionView in
                guard let viewHost = Introspect.findViewHost(from: introspectionView) else {
                    return nil
                }
                return viewHost
            },
            customize: customize
        ))
    }

    private func introspectTitlebarView(customize: @escaping (NSView) -> ()) -> some View {
        return inject(AppKitIntrospectionView(
            selector: { introspectionView -> NSView? in
                guard let viewHost = Introspect.findHostingView(from: introspectionView),
                      let superview = viewHost.superview
                else { return nil }

                let subviews = superview.subviews
                for subview in subviews {
                    if NSStringFromClass(type(of: subview)).contains("NSTitlebarContainerView") {
                        return subview
                    }
                }
                return nil
            },
            customize: customize
        ))
    }

    public func hideTitlebar() -> some View {
        return self
            .introspectView { view in
              guard let window = view.window else { return }
              window.isOpaque = false
              window.backgroundColor = .clear
            }
            .introspectTitlebarView { titleBarView in
                print(titleBarView)
                titleBarView.isHidden = true
            }
    }
}