Swift - 协议作为按钮动作的目标类型 [英] Swift - protocol as type as target of button action

问题描述

我正在尝试创建 - HeaderView，它是 UIView 的子类，它包含一个关闭按钮和一个标题标签.

I am trying to create - HeaderView which is subclass of UIView, it contains a close button and a title label.

class HeaderView: UIView {
    private var titleLabel: UILabel!
    private var closeButton: UIButton!
}

我不想将 self 添加为 closeButton 操作的目标，而是想将 myViewController 设置为其目标，而且我希望 HeaderView 类可重用.

I don't want to add self as target of closeButton action but want to set myViewController as its target, moreover I want HeaderView class to be reusable.

所以我声明了一个协议:

So I declared a protocol:

protocol CloseViewProtocol {
    func closeViewAction(sender: UIButton!)
}

并声明一个这样的变量:

And declared a variable like this:

class HeaderView: UIView {
    private var titleLabel: UILabel!
    private var closeButton: UIButton!

    var closeButtonTarget: CloseViewProtocol?
}

强制(在编译时)closeButtonTarget 实现 closeViewAction: 方法.

to enforce (at compile time) that closeButtonTarget implements closeViewAction: method.

现在我不能这样做:

closeButton.addTarget(closeButtonTarget, action: "closeViewAction:", forControlEvents: .TouchUpInside)

做哪个编译器抱怨 -

doing which compiler complains -

Cannot convert value of type 'CloseViewProtocol?' to expected argument type 'AnyObject?'

要解决这个问题，我可以这样做:

To resolve this I can do this:

let buttonTarget = closeButtonTarget as! UIViewController
closeButton.addTarget(buttonTarget, action: "closeViewAction:", forControlEvents: .TouchUpInside)

有没有更好的方法来实现预期的行为?

Is there any better way to achieve expected behavior?

推荐答案

我喜欢 Andrius 方法，但要回答这个问题，您必须将 class 关键字添加到协议的继承列表中:

I like Andrius approach, but to answer the question, you have to add the class keyword to your protocol’s inheritance list:

protocol CloseViewProtocol: class {
    func closeViewAction(sender: UIButton!)
}

这篇关于Swift - 协议作为按钮动作的目标类型的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！