Swift继承和类

Question

我正在自己学习swift，但我无法让这个代码运行，我正在尝试创建一个类“Inhabitant”，它继承了Person类的一个新的“Country”属性，有两个初始值设定项：-一个接受firstname和lastname，并将Country设置为空String-一个接收firstname，lastname和country，并创建String类型的计算属性描述，该描述返回由空格分隔的名字、姓氏和国家

class Person {
    var firstname: String
    var lastname: String
    var fullname: String {
        return firstname + " " + lastname
    }

    init(firstname: String, lastname: String) {
        self.firstname = firstname
        self.lastname = lastname
    }
}

    class Inhabitant: Person {
    var country: String? = nil
    var description: String {
        return firstname + " " + lastname + " " + country ?? ""
    }
    override init(firstname: String, lastname: String) {
        super.init(firstname: <#T##String#>, lastname: <#T##String#>)
        self.country = ""
    }
    init(firstname: String, lastname: String, Country: String) {
        super.init(firstname: <#T##String#>, lastname: <#T##String#>)
    }
}

func tst() {
    let perso = Inhabitant(firstname: "toto", lastname: "bobo")
    print(perso)
}

代码无法运行：

Editor placeholder in source file

Answer 1

我会做这样的事情：

class Person {
    var firstname: String
    var lastname: String
    var fullname: String {
        return firstname + " " + lastname
    }

    init(firstname: String, lastname: String) {
        self.firstname = firstname
        self.lastname = lastname
    }
}

class Inhabitant: Person {
    var country: String? = nil
    var description: String {
        //1
        return "\(firstname) \(lastname) \(country ?? "")"
    }
    override init(firstname: String, lastname: String) {
        //2
        super.init(firstname: firstname, lastname: lastname)
        self.country = ""
    }
    init(firstname: String, lastname: String, country: String) {
        super.init(firstname: firstname, lastname: lastname)
        self.country = country
    }
}

func tst() {
    let perso = Inhabitant(firstname: "toto", lastname: "bobo")
    let perso2 = Inhabitant(firstname: "toto", lastname: "bobo", country: "Belgium")
    print(perso.fullname)
    print(perso2.description)
}

tst()

解释：

< Li > swift中的字符串插值使用此语法完成，参见swift编程语言 < li >当您覆盖初始化器时，您想要的是将您收到的参数传递给您的超级初始化器。