如何在 Swift 中为 UIViewController 子类创建自定义初始值设定项? [英] How do I make a custom initializer for a UIViewController subclass in Swift?

问题描述

抱歉，如果之前有人问过这个问题，我已经搜索了很多，许多答案来自早期的 Swift 测试版，当时情况有所不同.我似乎找不到明确的答案.

Apologies if this has been asked before, I've searched around a lot and many answers are from earlier Swift betas when things were different. I can't seem to find a definitive answer.

我想继承 UIViewController 并有一个自定义初始值设定项，以便我可以轻松地在代码中进行设置.我在 Swift 中无法执行此操作.

I want to subclass UIViewController and have a custom initializer to allow me to set it up in code easily. I'm having trouble doing this in Swift.

我想要一个 init() 函数，我可以用它来传递特定的 NSURL 然后我将与视图控制器一起使用.在我看来，它看起来像 init(withImageURL: NSURL).如果我添加该函数，它会要求我添加 init(coder: NSCoder) 函数.

I want an init() function that I can use to pass a specific NSURL I'll then use with the view controller. In my mind it looks something like init(withImageURL: NSURL). If I add that function it then asks me to add the init(coder: NSCoder) function.

我相信这是因为它在超类中用 required 关键字标记?所以我必须在子类中做?我添加它:

I believe this is because it's marked in the superclass with the required keyword? So I have to do it in the subclass? I add it:

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

现在呢?我的特殊初始化器是否被认为是一种方便?指定的?我是否调用了超级初始化程序?来自同一个类的初始化程序?

Now what? Is my special initializer considered a convenience one? A designated one? Do I call a super initializer? An initializer from the same class?

如何将我的特殊初始化器添加到 UIViewController 子类中?

How do I add my special initializer onto a UIViewController subclass?

推荐答案

class ViewController: UIViewController {
        
    var imageURL: NSURL?
    
    // this is a convenient way to create this view controller without a imageURL
    convenience init() {
        self.init(imageURL: nil)
    }
    
    init(imageURL: NSURL?) {
        self.imageURL = imageURL
        super.init(nibName: nil, bundle: nil)
    }
    
    // if this view controller is loaded from a storyboard, imageURL will be nil
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
}

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