“#selector”指的是不公开给Objective-C的方法

The new Xcode 7.3 passing the parameter via addTarget usually works for me but in this case it's throwing the error in the title. Any ideas? It throws another when I try to change it to @objc

新的Xcode 7.3通过addTarget传递参数通常对我来说是可行的，但在这种情况下，它会在标题中抛出错误。什么好主意吗?当我试图将它改为@objc时，它会抛出另一个。

Thank you!

谢谢你！

cell.commentButton.addTarget(self, action: #selector(FeedViewController.didTapCommentButton(_:)), forControlEvents: UIControlEvents.TouchUpInside)

The selector it's calling

选择器调用

func didTapCommentButton(post: Post) {
}

3 个解决方案

#1

124

In my case the function of the selector was private. Once I removed the private the error was gone. Same goes for fileprivate.

在我的例子中，选择器的函数是私有的。一旦我删除了private，错误就消失了。fileprivate也是一样。

In Swift 4
You will need to add @objc to the function declaration. Until swift 4 this was implicitly inferred.

在Swift 4中，需要向函数声明中添加@objc。直到斯威夫特4被暗中推断。

#2

You need to use the @objc attribute on didTapCommentButton(_:) to use it with #selector.

需要使用didTapCommentButton(_:)上的@objc属性与#selector一起使用。

You say you did that but you got another error. My guess is that the new error is that Post is not a type that is compatible with Objective-C. You can only expose a method to Objective-C if all of its argument types, and its return type, are compatible with Objective-C.

你说你那样做了，但你又犯了一个错误。我猜想新的错误是Post不是与Objective-C兼容的类型。如果所有的参数类型及其返回类型都与Objective-C兼容，则只能向Objective-C公开一个方法。

You could fix that by making Post a subclass of NSObject, but that's not going to matter, because the argument to didTapCommentButton(_:) will not be a Post anyway. The argument to an action function is the sender of the action, and that sender will be commentButton, which is presumably a UIButton. You should declare didTapCommentButton like this:

您可以通过使Post成为NSObject的子类来修复它，但这并不重要，因为didTapCommentButton(_:)的参数无论如何都不是Post。动作函数的参数是动作的发送方，那个发送方将是commentButton，这可能是一个UIButton。你应该像这样声明didTapCommentButton:

@objc func didTapCommentButton(sender: UIButton) {
    // ...
}

You'll then face the problem of getting the Post corresponding to the tapped button. There are multiple ways to get it. Here's one.

然后，您将面临这样的问题:获取与所单击的按钮对应的Post。有多种方法可以得到它。这是一个。

I gather (since your code says cell.commentButton) that you're setting up a table view (or a collection view). And since your cell has a non-standard property named commentButton, I assume it's a custom UITableViewCell subclass. So let's assume your cell is a PostCell declared like this:

我收集(因为您的代码是cell.commentButton)您正在设置一个表视图(或集合视图)。由于您的单元格有一个名为commentButton的非标准属性，我假设它是一个自定义的UITableViewCell子类。假设你的单元格是这样声明的后单元格

class PostCell: UITableViewCell {
    @IBOutlet var commentButton: UIButton?
    var post: Post?

    // other stuff...
}

Then you can walk up the view hierarchy from the button to find the PostCell, and get the post from it:

然后您可以从按钮上向上走视图层次结构，找到PostCell，并从中获取post:

@objc func didTapCommentButton(sender: UIButton) {
    var ancestor = sender.superview
    while ancestor != nil && !(ancestor! is PostCell) {
        ancestor = view.superview
    }
    guard let cell = ancestor as? PostCell,
        post = cell.post
        else { return }

    // Do something with post here
}

#3

Try having the selector point to a wrapper function, which in turn calls your delegate function. That worked for me.

尝试让选择器指向包装器函数，包装器函数反过来调用委托函数。为我工作。

cell.commentButton.addTarget(self, action: #selector(wrapperForDidTapCommentButton(_:)), forControlEvents: UIControlEvents.TouchUpInside)

- - - - - -

func wrapperForDidTapCommentButton(post: Post) {
     FeedViewController.didTapCommentButton(post)
}

#1

124