extension UIView {
   func getSpecifiedSubviews<T: UIView>() -> [T] {
        var subviews = [T]()
        self.subviews.forEach { subview in
            subviews += subview.getSpecifiedSubviews() as [T]
            if let subview = subview as? T {
                subviews.append(subview)
            }
        }
        return subviews
    }
}

// Ex: let allTextField: [UITextField] = self.getSpecifiedSubviews()