'#selector' refers to a method that is not exposed to Objective-C

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

Thank you!

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

The selector it's calling

func didTapCommentButton(post: Post) {
}

As you know `selector`[<sup>\[About\]</sup>][1] says that `Objective-C runtime`[<sup>\[About\]</sup>][2] should be used. Declarations that are marked as `private` or `fileprivate` are not exposed to the Objective-C runtime **by default**. That is why you have two variants:

1. Mark your `private` or `fileprivate` method declaration by `@objc`[<sup>\[About\]</sup>][2]
2. Use `internal`, `public`, `open` method access modifier[<sup>\[About\]</sup>][3]


[1]:

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

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

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

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

-

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

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

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.

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:

@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.

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:

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:

@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
}