swift继承

1、属性的继承

子类可以继承父类的属性，包括存储属性、计算属性和类型属性

class Person{
    //存储属性
    var age = 20
    //计算属性
    var description: String{
        return "我现在\(self.age)岁了"
    }
    //类型属性
    static var kind = "Chinese"
}
class Teacher : Person{}
let teacher = Teacher()
print(teacher.age,teacher.description,"\(Teacher.kind)")

控制台：

20 我现在20岁了 Chinese

2、属性观察器的继承

class Person{
    //存储属性
    var age = 20{
        willSet{
            print("age即将被赋值\(newValue)")
        }
        didSet{
            if(age > oldValue){
                print("新赋值的值比原来的大")
            }else{
                print("新赋值的值比原来的小")
            }
        }
    }
}
class Teacher : Person{}
var t:Teacher = Teacher()
t.age = 19

控制台：

age即将被赋值19
新赋值的值比原来的小

3、下标脚本的继承

class Person{
    subscript (index:Int) -> String{
        switch index{
        case 1:
            return "1"
        case 2:
            return "2"
        case 3:
            return "3"
        default:
            return "default"
        }
    }
}
class Teacher : Person{}
let teacher = Teacher()
print(teacher[1],teacher[6])

控制台：

1 default

4、方法的继承

包括对象方法和类方法

class Person{
    func description(){
        print("我是Person的方法")
    }
}
class Teacher : Person{}
let teacher = Teacher()
teacher.description()

控制台：

我是Person的方法

5、增加新属性和方法

class Person{
    subscript (index:Int) -> String{
        switch index{
        case 1:
            return "1"
        case 2:
            return "2"
        case 3:
            return "3"
        default:
            return "default"
        }
    }
    func run(){
        print("Person is running")
    }
}
class Teacher : Person{
    let age = 15
    func walk(){
        print("Teacher is walking")
    }
}
let person = Person()
let teacher = Teacher()
person.run()
teacher.walk()
print(teacher.age)

控制台：

Person is running
Teacher is walking
15