Overriding target of UIPanGestureRecognizer

Question

I have a base class which handles some basic animations of the cell. In my sub class, I have overridden the recognizer target and want to do some other stuff, but the translation is always 0 because I call in the base class the translation is being reset to .zero.

Is there a way I can have my base class to do the basic animation and using a sub class to override the method and do some other stuff as shown below?

I have a baseclass:

class Base: UITableViewCell {

    override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)

        let gesture = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
        addGestureRecognizer(gesture)
    }

    func handlePan(recognizer: UIPanGestureRecognizer) {
        if recognizer.state == .changed {
            let translation = recognizer.translation(in: self)

            ...

            recognizer.setTranslation(.zero, in: self)
        }
    }
}

And my subclass:

class Sub: Base {

    override func handlePan(recognizer: UIPanGestureRecognizer) {
        super.handlePan(recognizer: recognizer)

        if recognizer.state == .changed {
            let translation = recognizer.translation(in: self)

            print(translation.x) // is always 0

            recognizer.setTranslation(.zero, in: self)
        }
    }
}

Answer 1

In the base class could you split out the common functionality into a different function? That way you wouldn't need to call super.handlePan:

class Base: UITableViewCell {
    override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        let gesture = UIPanGestureRecognizer(target: self, action: #selector(handlePan))
        addGestureRecognizer(gesture)
    }

    func handlePan(recognizer: UIPanGestureRecognizer) {
        if recognizer.state == .changed {
            let translation = recognizer.translation(in: self)
            performBaseAnimation(recognizer)
            recognizer.setTranslation(.zero, in: self)
        }
    }
    func performBaseAnimation(_ recognizer: UIPanGestureRecognizer) {
        // perform common actions here
    }
}
class Sub: Base {
    override func handlePan(recognizer: UIPanGestureRecognizer) {
        super.handleBaseAnimation(recognizer)
        if recognizer.state == .changed {
            // perform subclass actions here
        }
    }
}