Pass UILongPressGestureRecognizer between UIViewControllers - ios

Question

I've looked around on SO and other places online and haven't been able to find a solution yet. I have a UILongPressGestureRecognizer on one view controller which performs an animation on a UIView then presents another view controller (if the user does not move their finger during the animation). I would like to dismiss the second view controller when the user lifts their finger, but I am having trouble.
My current approach is adding another UILongPressGestureRecognizer to the second view controller and dismissing the view controller when its state is .ended; however I don't know how to tie the two gesture recognizers together so that I can start the touch in one view controller and end in another.
I have attached the relevant code below
In the first View Controller
#objc private func pinAnimation(sender: UILongPressGestureRecognizer) {
if let headerView = projectView.projectCollectionView.supplementaryView(forElementKind: UICollectionElementKindSectionHeader, at: IndexPath(row: 0, section: 0)) as? ProjectHeaderView {
switch sender.state {
case .began:
let frame = headerView.pinButton.frame
UIView.setAnimationCurve(.linear)
UIView.animate(withDuration: 1, animations: {
headerView.pinProgressView.frame = frame
}, completion: { (_) in
if (headerView.pinProgressView.frame == headerView.pinButton.frame) {
let notification = UINotificationFeedbackGenerator()
notification.notificationOccurred(.success)
let homeVC = HomeViewController()
self.present(homeVC, animated: true, completion: {
homeVC.longPress(sender)
let height = headerView.pinButton.frame.height
let minX = headerView.pinButton.frame.minX
let minY = headerView.pinButton.frame.minY
headerView.pinProgressView.frame = CGRect(x: minX, y: minY, width: 0, height: height)
})
}
})
case .ended:
//cancel current animation
let height = headerView.pinProgressView.frame.height
let minX = headerView.pinProgressView.frame.minX
let minY = headerView.pinProgressView.frame.minY
UIView.setAnimationCurve(.linear)
UIView.animate(withDuration: 0.5) {
headerView.pinProgressView.frame = CGRect(x: minX, y: minY, width: 0, height: height)
}
default:
break
}
}
}
In the second View Controller
override func viewDidLoad() {
super.viewDidLoad()
let longPressRecognizer = UILongPressGestureRecognizer(target: self, action: #selector(longPress(_:)))
view.addGestureRecognizer(longPressRecognizer)
}
#objc func longPress(_ sender: UILongPressGestureRecognizer) {
switch sender.state {
case .ended:
self.dismiss(animated: true, completion: nil)
default:
break
}
}
Any help / guidance will be much appreciated!

Answer 1

I would recommend you using delegate pattern:
Create delegate for your first ViewController
protocol FirstViewControllerDelegate {
func longPressEnded()
}
then add delegate variable to your first ViewController
class FirstViewController {
var delegate: FirstViewControllerDelegate?
...
}
next call method on delegate when long press ended
#objc private func pinAnimation(sender: UILongPressGestureRecognizer) {
...
switch sender.state {
case .began:
...
case .ended:
...
delegate?.longPressEnded()
default:
break
}
}
after that when you're presenting second ViewController, set first ViewController's delegate as homeVC
let homeVC = HomeViewController()
self.delegate = homeVC
then implement this delegate to second ViewController and define what should happen when long press ended
class HomeViewController: UIViewController, FirstViewControllerDelegate {
...
func longPressEnded() {
dismiss(animated: true, completion: nil)
}
}