Can I make #selector refer to a closure in Swift?

Question

I want to make a selector argument of my method refer to a closure property, both of them exist in the same scope. For example,

func backgroundC         


        

Answer 1

I tried this for UIBarButtonItem at least:

private var actionKey: Void?

extension UIBarButtonItem {

    private var _action: () -> () {
        get {
            return objc_getAssociatedObject(self, &actionKey) as! () -> ()
        }
        set {
            objc_setAssociatedObject(self, &actionKey, newValue, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC)
        }
    }

    convenience init(title: String?, style: UIBarButtonItemStyle, action: @escaping () -> ()) {
        self.init(title: title, style: style, target: nil, action: #selector(pressed))
        self.target = self
        self._action = action
    }

    @objc private func pressed(sender: UIBarButtonItem) {
        _action()
    }

}

Then you can do this:

navigationItem.leftBarButtonItem = UIBarButtonItem(title: "Test", style: .plain, action: {
    print("Hello World!")
})