Swift 3 protocol extension using selector error

Question

I have what I thought to be a very simple protocol extension for my UIViewControllers providing the capability to dismiss a keyboard through a tap gesture. Here

Answer 1

Matt's answer is correct. However, I would just add that, if you are dealing with #selector to use from a NotificationCenter notification, you could try to avoid #selector by using the closure version.

Example:

Instead of writing:

extension KeyboardHandler where Self: UIViewController {

    func startObservingKeyboardChanges() {

        NotificationCenter.default.addObserver(
            self,
            selector: #selector(keyboardWillShow(_:)),
            // !!!!!            
            // compile error: cannot be included in a Swift protocol
            name: .UIKeyboardWillShow,
            object: nil
        )
    }

     func keyboardWillShow(_ notification: Notification) {
       // do stuff
    }
}

you could write:

extension KeyboardHandler where Self: UIViewController {

    func startObservingKeyboardChanges() {

        // NotificationCenter observers
        NotificationCenter.default.addObserver(forName: .UIKeyboardWillShow, object: nil, queue: nil) { [weak self] notification in
            self?.keyboardWillShow(notification)
        }
    }

    func keyboardWillShow(_ notification: Notification) {
       // do stuff
    }
}