这个继承关系类的具体实现代码如下：

class Person { var name: String var age: Int func description() -> String { return "\(name) 年龄是: \(age)" } convenience init () { self.init(name: "Tony") self.age = 18 } convenience init (name: String) { self.init(name: name, age: 18) } init (name: String, age: Int) { self.name = name self.age = age } } class Student: Person { var school: String init (name: String, age: Int, school: String) { self.school = school super.init(name: name, age: age) } } class Worker: Person { var factory: String init (name: String, age: Int, factory: String) { self.factory = factory super.init(name: name, age: age) } }

下面看一个示例：

let student1 = Student(name: "Tom", age: 18, school: "清华大学") let student2 = Student(name: "Ben", age: 28, school: "北京大学") let student3 = Student(name: "Tony", age: 38, school: "香港大学") let worker1 = Worker(name: "Tom", age: 18, factory: "钢厂") let worker2 = Worker(name: "Ben", age: 20, factory: "电厂") let people = [student1, student2, student3, worker1, worker2] for item in people { if let student = item as? Student { print("Student school: \(Student.school)") } else if let worker = item as? Worker { print("Worker factory: \(Worker.factory)") } }

操作符在转换的同时进行隐式拆包。

示例代码如下：... let people = [student1, student2, student3, worker1, worker2] ... let stud1 = people[0] as? Student //people数组的第一个元素 print(stud1) print(stud1!.name) let stud2 = people[1] as! Student //people数组的第二个元素 print(stud2) print(stud2.name)

 

 

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