<分区>
我在 Swift 中收到一个我不理解的错误。这是我的 Playground 上的代码:
class Person : CustomStringConvertible
{
let Name :String;
let DoB :NSDate?
init(name :String, dob :NSDate?)
{
Name = name;
DoB = dob;
}
func age() -> Double {
let now = NSDate();
let age :Double = now.timeIntervalSinceDate(self.DoB!);
return age;
}
var description : String {
return "Name: \(Name), Age: \(self.age())";
}
}
extension NSDate {
static func dateFromComponents(year :Int, month :Int, day :Int) -> NSDate {
let components = NSDateComponents();
components.year = year;
components.month = month;
components.day = day;
return components.date!;
}
}
let helena = Person(name: "Helena", dob: NSDate.dateFromComponents(1986, month: 8, day: 10));
print(helena);