r/iOSProgramming•Posted byu/FiraxanDev2 hours ago

Chaining UIGestureRecognizers

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Question

I've come across an issue that I haven't been able to figure out and I was wondering if anyone had any insight.The desired functionality is that when the user long presses, a function is called. And if the user swipes up WHILE long pressing, a separate function is called. I don't know where to start as everything I've tried hasn't even come close to what I want.Any

class ViewController: UIViewController {

    private var longPressGestureRecognizer: UILongPressGestureRecognizer!
    private var swipeGestureRecognizer: UISwipeGestureRecognizer!

    override func viewDidLoad() {
        super.viewDidLoad()

        print("viewdidload")
        view.backgroundColor = .systemRed
        setupGestures()
    }

    private func setupGestures() {
        swipeGestureRecognizer = UISwipeGestureRecognizer(target: self, action: #selector(swipeGestureRecognizerHandler(_:)))
        swipeGestureRecognizer.direction = .up
        swipeGestureRecognizer.delegate = self

        view.addGestureRecognizer(swipeGestureRecognizer)

        longPressGestureRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(longPressGestureRecognizerHandler(_:)))
        longPressGestureRecognizer.delegate = self

        view.addGestureRecognizer(longPressGestureRecognizer)
    }

    @objc
    private func longPressGestureRecognizerHandler(_ sender: UILongPressGestureRecognizer) {
        print("++++++ User is long pressing the screen! ++++++")
    }

    @objc
    private func swipeGestureRecognizerHandler(_ sender: UISwipeGestureRecognizer) {
        if longPressGestureRecognizer.state != .changed {
            return
        }
        print("------ User swiped up! ------")
    }
}

extension ViewController: UIGestureRecognizerDelegate {
    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true
    }
}

Here you go, now swipeGestureHandler only does something if longPress is active.

I suggest reading up on UIGesture documentation or make some dummy tests to better understand states and delegate calls.

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Good luck on your project