print Hierarchy

extension UIView {
    func printSubView(){
        printSubViewH(self, "")
    }
    private func printSubViewH(_ view: UIView, _ str: String){
        print(str + view.description)
        let nextstr = str + "   "
        for view in view.subviews{
            printSubViewH(view, nextstr)
        }
    }
}