How can I stop access to all NSView in a window after showing a new NSView on the whole window?

Question

Let's say I have n number of views in a window but I want to restrict access to all of them and show a signInView above that and till the signIn is completed it should not let access to any other view under it. But at the moment, even if I can show the signInView(), the views under that are accessed.

I am showing the sign in view in the window like:

vc = SignInViewController()

self.view.window?.contentViewController?.view.addSubview(vc.view)