How can you add a UIGestureRecognizer to a UIBarButtonItem as in the common undo/redo UIPopoverController scheme on iPad apps?

Question

Problem

In my iPad app, I cannot attach a popover to a button bar item only after press-and-hold events. But this seems to be standard for

Answer 1

Ready for use UIBarButtonItem subclass:

@objc protocol BarButtonItemDelegate {
    func longPress(in barButtonItem: BarButtonItem)
}

class BarButtonItem: UIBarButtonItem {
    @IBOutlet weak var delegate: BarButtonItemDelegate?
    private let button = UIButton(type: .system)

    override init() {
        super.init()
        setup()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }

    private func setup() {
        let recognizer = UILongPressGestureRecognizer(
            target: self,
            action: #selector(longPress)
        )
        button.addGestureRecognizer(recognizer)
        button.setImage(image, for: .normal)
        button.tintColor = tintColor
        customView = button
    }

    override var action: Selector? {
        set {
            if let action = newValue {
                button.addTarget(target, action: action, for: .touchUpInside)
            }
        }
        get { return nil }
    }

    @objc private func longPress(sender: UILongPressGestureRecognizer) {
        if sender.state == .began {
            delegate?.longPress(in: self)
        }
    }
}