在Swift和init（windowNibName）中将NSWindowController子类化 [英] Subclassing NSWindowController in Swift and init(windowNibName)

问题描述

我想在Swift中启动一个基于Cocoa项目的新文档，并希望创建一个 NSWindowController 的子类（如Apple的指南中关于基于文档的应用程序所推荐的）。在ObjC中，您将创建一个发送 initWithWindowNibName：消息的 NSWindowController 子类的实例，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 init（windowNibName）只能作为方便初始化器， code> NSWindowController 是 init（window）这显然需要我在一个窗口中传递。

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.

我不能从我的子类调用 super.init（windowNibName），因为它不是指定的初始化程序，所以我显然必须实现 convenience init（windowNibName），这需要调用 self.init（window）。

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

如果我有nib文件，我怎么访问nib文件的窗口发送给初始化程序？需要重写 NSWindowController （ init（）， init ）和 init（coder））或者没有一个，在这种情况下你的子类会自动继承 init ）和所有其他的便利初始化器，你将能够使用超类的方便初始化器构造它：

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")

这是由Initialization / Automatic Initializer Inheritance语言指南：

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

但是，如果满足某些条件，超类初始化器将自动继承。在实践中，这意味着你不需要在许多常见的场景中编写初始化器覆盖，并且只要安全就可以继承你的超类初始化器。

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，以下两个规则适用：

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，它会自动继承其所有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
如果你的子类提供了所有其超类指定的初始化器的实现，或者通过按照规则1继承它们，或者通过提供一个自定义实现作为其定义的一部分，那么它将自动继承所有的超类方便初始化器。

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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