inheritance - 理解swift语言中的去初始化和继承

Question

假设我有两个类:基类和子类，如下所示:

class Base{
    var name: String?
    init() {
       name = "The base class"
    }

    deinit {
       println("call Deinitialization in base class")
       name = nil
    }
}

class Sub: Base{
    var subName: String?
    init() {
     super.init()
     subName = "The sub class"
    }

    deinit {
       println("call Deinitialization in sub class")
       subName = nil
       // does it really call super.deinit() ?
       // or assign name = nil ?
    }
}

调用子类的析构函数时，是否调用super.deinit()将nil赋值给name变量？或者我必须在子类的析构器中手动赋值？

Answer 1

您可以选择在您的子类中有一个deinit。

如果你这样做

    let x = Sub()

你会看到首先调用的 deinit 是 Sub() 中的那个，然后是 base deinit 被调用。所以是的，super.deinit() 被调用但是在子类之后。

书中还说(第 286 页):

You are not allowed to call a deinitializer yourself. Superclass deinitializers are inherited by their subclasses, and the superclass deinitializer is called automatically at the end of a subclass deinitializer implementation. Superclass deinitializers are always called, even if a subclass does not provide its own deinitializer.

摘自:Apple Inc.“The Swift Programming Language”。电子书。 https://itun.es/us/jEUH0.l