今天学swift的时候遇到一个问题,无法创建一个空的类对象。最主要的是,无法让对象的类变量为空。比如创建一个Person类,年龄age用Int属性,但是age默认是0,不是空值nil。以下代码给出了解决方案:
import Foundation
class Person {
//element variables
var country: String
var firstName: String
var lastName: String
var age: Int?//if there's no value of age, age = nil
//instructor
init(country: String, firstName: String, lastName: String/*, age: Int*/) {
self.country = country
self.firstName = firstName
self.lastName = lastName
//self.age = age
}
}