Extensions.swift  =>

import Foundation

import UIKit

// MARK:- UIView

extension UIView {

    func updateView() {

        for view in self.subviews {

            view.updateView()

        }

    }

}

BasicallyView.swift =>

import UIKit

class BasicallyView: UIView {

 override func updateView() {

        super.updateView()

    }

}

自定义的View =>

  override func updateView() {

        super.updateView()

        //写自己需要的代码,如下

        self.backgroundColor = UIColor.clear

    }

Swift:一般继承父类的写法