swift - 当 init NSCoder 是 Swift 中基类中的便捷方法时，正确地在子类中初始化 NSCoder

Question

这是我的代码:

import Foundation


class Person: NSObject, NSCoding {

var name: String



init(name: String) {
    self.name = name
}

func encodeWithCoder(aCoder: NSCoder) {
    aCoder.encodeObject(name, forKey: "name")
}

required convenience init?(coder aDecoder: NSCoder) {

    let name = aDecoder.decodeObjectForKey("name") as! String

    self.init(name: name)

}  
}


class Martin: Person {

 init() {
    self.init(name: "Martin")
}

required convenience init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
}

}

let p = Martin()

print(p.name)

出于某种原因，我总是以第 22 条军规告终，我认为使这项工作有效的唯一方法是显式初始化 required convenience init?(coder aDecoder: NSCoder) 中的所有属性能够消除便利并在 Martin

中执行 super.init(coder: aDecoder)

我阅读了 Swift 中的 init 规则，仍然不明白为什么 Martin 在这种情况下不能从 Person 继承 convenience init。

Answer 1

因为 the rules声明

1. A designated initializer must call a designated initializer from its immediate superclass.
2. A convenience initializer must call another initializer from the same class.
3. A convenience initializer must ultimately call a designated initializer.