Using UIAppearance and switching themes

Question

I\'m looking to theme my iOS app and have been reading up on UIAppearance. I want the user to be able to switch between a number of different visual themes from within the a

Answer 1

swift 4:

let windows = UIApplication.shared.windows
for window in windows {
    for view in window.subviews {
        view.removeFromSuperview()
        window.addSubview(view)
    }
}