How to extend an Objective-C class with Swift in a framework?

In a similar case, Tie's answer really helped me but it didn't work for me, I had to add @objc for the method:

public extension SearchBarWidget {
    @objc public func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
        self.endEditing(true)
    }
}

The SearchBarWidget class was @objc public signatured.

Have you tried making the extension and function public?

public extension Sample {
    public func PrettyPrint () {    
        print("\(x)")
    }
}