Create Spotlight-like window in Swift 4?

问题

I want to create a window as part of my app which is displaying a Spotlight-like window after hitting a certain keystroke.

But all I got is to hide the title:

override func viewWillAppear() {
    self.view.window?.titleVisibility = .hidden
    self.view.window?.titlebarAppearsTransparent = true
    self.view.window?.styleMask.insert(.fullSizeContentView)
}

Which results in:

How can I create such a view with Xcode 10 and Swift?

来源：https://stackoverflow.com/questions/54054473/create-spotlight-like-window-in-swift-4