在 Swift 和 init(windowNibName) 中继承 NSWindowController [英] Subclassing NSWindowController in Swift and init(windowNibName)

问题描述

我正在尝试在 Swift 中启动一个新的基于文档的 Cocoa 项目，并且想要创建一个 NSWindowController 的子类(如 Apple 的基于文档的应用程序指南中所推荐).在 ObjC 中，您将创建一个 NSWindowController 子类的实例，发送 initWithWindowNibName: 消息，该消息相应地实现，调用超类方法.

I am trying to start a new document based Cocoa project in Swift and want to create a subclass of NSWindowController (as recommended in Apple's guides on document based apps). In ObjC you would make an instance of an NSWindowController subclass sending the initWithWindowNibName: message, which was implemented accordingly, calling the superclasses method.

在 Swift 中 init(windowNibName) 仅作为便利初始化器使用，NSWindowController 的指定初始化器是 init(window) 显然要我通过一个窗口.

In Swift init(windowNibName) is only available as an convenience initializer, the designated initializer of NSWindowController is init(window) which obviously wants me to pass in a window.

我不能从我的子类中调用super.init(windowNibName)，因为它不是指定的初始化器，所以我显然要实现convenience init(windowNibName)，这反过来需要调用self.init(window).但是如果我只有我的 nib 文件，我如何访问 nib 文件的窗口以发送到该初始化程序?

I cannot call super.init(windowNibName) from my subclass, because it is not the designated initializer, so I obviously have to implement convenience init(windowNibName), which in turn needs to call self.init(window). But if all I have is my nib file, how do I access the nib file's window to send to that initializer?

推荐答案

您需要覆盖 NSWindowController (init(), init(window) 和 init(coder))，或者都没有，在这种情况下，您的子类将自动继承 init(windowNibName) 和所有其他便利初始化器，您将能够使用超类的便利初始化器来构造它:

You need to override either all three designated initializers of NSWindowController (init(), init(window) and init(coder)), or none of them, in which case your subclass will automatically inherit init(windowNibName) and all others convenience initializers and you will be able to construct it using superclass's convenience initializer:

// this overrides none of designated initializers
class MyWindowController: NSWindowController {
    override func windowDidLoad() {
        super.windowDidLoad()
    }
}

// this one overrides all of them
//
// Awkwardly enough, I see only two initializers 
// when viewing `NSWindowController` source from Xcode, 
// but I have to also override `init()` to make these rules apply.
// Seems like a bug.
class MyWindowController: NSWindowController
{
    init()
    {
        super.init()
    }

    init(window: NSWindow!)
    {
        super.init(window: window)
    }

    init(coder: NSCoder!)
    {
        super.init(coder: coder)
    }

    override func windowDidLoad() {
        super.windowDidLoad()
    }
}

// this will work with either of the above
let mwc: MyWindowController! = MyWindowController(windowNibName: "MyWindow")

语言指南中的初始化/自动初始化程序继承"涵盖了这一点:

This is covered by "Initialization / Automatic Initializer Inheritance" in the language guide:

然而，如果满足某些条件，超类初始值设定项会自动继承.在实践中，这意味着您不需要在许多常见场景中编写初始化器重写，并且可以在安全的情况下以最少的努力继承您的超类初始化器.

However, superclass initializers are automatically inherited if certain conditions are met. In practice, this means that you do not need to write initializer overrides in many common scenarios, and can inherit your superclass initializers with minimal effort whenever it is safe to do so.

假设您为在子类中引入的任何新属性提供默认值，以下两条规则适用:

Assuming that you provide default values for any new properties you introduce in a subclass, the following two rules apply:

规则 1如果你的子类没有定义任何指定的初始化器，它会自动继承它所有的超类指定的初始化器.

Rule 1 If your subclass doesn’t define any designated initializers, it automatically inherits all of its superclass designated initializers.

规则 2如果您的子类提供了其所有超类指定初始值设定项的实现(通过按照规则 1 继承它们，或通过提供自定义实现作为其定义的一部分)，则它会自动继承所有超类便利初始值设定项.

Rule 2 If your subclass provides an implementation of all of its superclass designated initializers—either by inheriting them as per rule 1, or by providing a custom implementation as part of its definition—then it automatically inherits all of the superclass convenience initializers.

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