import Foundation

// 定义一个具有一些属性的类
class Person {
   let name: String
   let age: Int
   let country: String

   init(name: String, age: Int, country: String) {
      self.name = name
      self.age = age
      self.country = country
   }
}

// 定义一个结构体来保存弱引用
struct Weak<T: AnyObject> {
   weak var value: T?

   init(_ value: T?) {
      self.value = value
   }
}

// 声明对 Person 实例的弱引用数组
var personArray: [Weak<Person>] = []

// 创建 Person 的一个实例，并将其弱引用添加到数组中
let anil = Person(name: "Anil Kumar", age: 25, country: "India")
personArray.append(Weak(anil))

// 显示详情
print("Person Name: \(anil.name), age: \(anil.age) and country: \(anil.country)")

Person Name: Anil Kumar, age: 25 and country: India

import Foundation

// 为将由 Person 类使用的委托定义协议
protocol PersonClassDelegate: AnyObject {
   func personDidUpdateValue(_ person: Person)
}

// 定义一个 Person 类，该类使用对其委托的弱引用
class Person {
   weak var delegate: PersonClassDelegate?
   var age: Int = 0 {
      didSet {
         delegate?.personDidUpdateValue(self)
      }
   }
}

// 定义一个结构体，其中将保存对类型为 T 的对象的弱引用
struct Weak<T: AnyObject> {
   weak var value: T?

   init(_ value: T?) {
      self.value = value
   }
}

// 定义一个类，用于管理对 Person 实例的弱引用数组
class PersonClassManager: PersonClassDelegate {
   var weakArray: [Weak<Person>] = []

   func addPerson(_ person: Person) {
      person.delegate = self
      weakArray.append(Weak(person))
   }

   func personDidUpdateValue(_ person: Person) {
      print("Person class did update age to \(person.age)")
   }
}

// 创建一个 PersonClassManager 实例，并添加两个 Person 实例
let manager = PersonClassManager()
let person1 = Person()
let person2 = Person()
manager.addPerson(person1)
manager.addPerson(person2)

// 更新 person1 和 person2 的值
person1.age = 25
person2.age = 28

// 检查对 person1 和 person2 的弱引用是否仍然有效
for weakPerson in manager.weakArray {
   if let person = weakPerson.value {
      print("Person class with age \(person.age) still exists")
   } else {
      print("Person class has been deallocated")
   }
}

Person class did update age to 25
Person class did update age to 28
Person class with age 25 still exists
Person class with age 28 still exists