import Foundation
import Glibc

// 基类
class Books{
   var bookName: String

   init(bookName:String){
      self.bookName = bookName
   }
   func display() {
      print("Book are the best friends")
   }
}

// 子类
class Author:Books{
   override init(bookName:String){

      // 调用超级类的初始化程序
      super.init(bookName:bookName)
   }
   override func display(){

      // 调用超级类实现
      super.display()
      print("Author name is sohan")

   }
}

// 创建子类实例
let obj = Author(bookName: "Somita")
obj.display()

Book are the best friends
Author name is sohan