编辑代码

class SuperClass{
    func show() -> Void {
        print("这是超类SuperClass")
    }
    var number : Int = 0
    init(number:Int){
        self.number = number
    }
    var info : String {
        get{
            let N = number
            return "你的学号是\(N)"
        }
    }
    //final var group : Int = 0
    var group : Int = 0
}



class SubClass : SuperClass{
    override func show() -> Void{
        print("这是子类SupClass")
    }
    override var number : Int{
        didSet{
            if number < 0 {
                number = 0
            }
        }
    }
    override var group : Int{
        get {
           return number%5
        }
        set {
            super.group =  newValue
        }
    } 
    override var info :String {
        let G = group
        return super.info + ",你属于第\(G)组"
    }

}

let superClass = SuperClass(number:0)
let supClass = SubClass(number:2020967018)
superClass.show()
supClass.show()
print(superClass.group)
print(supClass.group)
print(supClass.info)