Adding GestureRecognizer to UIView won't trigger action - ios

Question

I have no idea why this gesture recognizer is not working as intended:
class SlideInMenuLauncher: NSObject, UITableViewDelegate, UITableViewDataSource {
fileprivate let dimmerView = UIView()
fileprivate let tableView: UITableView = {
let tbv = UITableView(frame: .zero)
return tbv
}()
fileprivate let resourceArray: [Content]
weak var delegate: SlideInMenuDelegate?
let cellIdentifier = "SlideInMenuTableViewCell"
init(withContentArray contentArray: [Content]) {
resourceArray = contentArray
super.init()
tableView.dataSource = self
tableView.delegate = self
tableView.register(UINib(nibName: cellIdentifier, bundle: nil), forCellReuseIdentifier: cellIdentifier)
}
func showMenu() {
if let window = UIApplication.shared.keyWindow {
dimmerView.backgroundColor = UIColor(white: 0, alpha: 0.5)
dimmerView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(dismissMenu)))
dimmerView.isUserInteractionEnabled = true
window.addSubview(dimmerView)
window.addSubview(tableView)
let height: CGFloat = 200
let y = window.frame.height - height
tableView.frame = CGRect(x: 0, y: window.frame.height, width: window.frame.width, height: height)
dimmerView.frame = window.frame
dimmerView.alpha = 0
UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 1, initialSpringVelocity: 1, options: .curveEaseOut, animations: {
self.dimmerView.alpha = 1
self.tableView.frame = CGRect(x: 0, y: y, width: self.tableView.frame.width, height: self.tableView.frame.height)
}, completion: nil)
}
}
func dismissMenu() {
UIView.animate(withDuration: 0.5) {
self.dimmerView.alpha = 0
if let window = UIApplication.shared.keyWindow {
self.tableView.frame = CGRect(x: 0, y: window.frame.height, width: self.tableView.frame.width, height: self.tableView.frame.height)
}
}
}
I've put a breakpoint in the dismissMenu function but it is never triggered. Perhaps my tired eyes (and mind) missed something simple?
Here I am adding the code where I actually call this class in case something is wrong there:
///Some other VC
let slideInMenuLauncher = SlideInMenuLauncher(withContentArray: [content])
slideInMenuLauncher.showMenu()

Answer 1

I would expect that to give a compiler error. You're missing the #objc declaration on your dismissMenu() function.
I added a view to a view controller in a storyboard and used a small variant of your code and it responds to taps just fine. Thus my guess is that there's something wrong with the way you're adding your views to the view controller.
EDIT:
I know what the problem is: If you set a view's alpha to 0 it stops responding to taps. Try setting the view's opaque flag to false and setting it's background color to clearColor.
Here's the code from the test project I created:
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var tapView: UIView!
override func viewDidLoad() {
super.viewDidLoad()
tapView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(handleTap)))
tapView.isUserInteractionEnabled = true
}
#objc func handleTap() {
print("You tapped on the view")
}
}

Answer 2

Can you try instead of this:
window.addSubview(dimmerView)
window.addSubview(tableView)
Do this:
window.addSubview(dimmerView)
window.addSubview(tableView)
window.bringSubviewToFront(dimmerView)

Answer 3

Try use following code:
let tapGes = UITapGestureRecognizer(target: self, action:#selector(dismissMenu))
tapGes.delegate = self
dimmerView.addGestureRecognizer(tapGes)
Hope it help you!

Answer 4

I think your problem is here:
dimmerView.alpha = 0
If I remember correctly, views that have their alpha set to 0 don't get touches. Try setting is to something like 0.5 just to see if it works, and then dial it back to a smaller value that's still greater than 0.

Answer 5

So I found the problem thanks to this post. When I was using the slideInMenuLauncher class elsewhere, I was not saving it to a strong reference or anything, so once I moved out of the scope of the function where I created the menu, the SlideInMenuLauncher object I used to create the dimmerView and tableView disappeared (despite still being able to see the views). Once I tapped the dimmerView the gesture recognizer sent a message to an object that no longer existed.
Setting the object to a strong property fixed the issue.