CODEWITHSUNDEEP
iosswiftuitapgesturerecognizer
A.Alqadomi
A.Alqadomi

Reputation: 1589

UITapGestureRecognizer is not working properly if the target is a normal class

I have a simple ViewController which have a single View in the middle, when I add a UITapGestureRecognizer it will work properly but when I try the same thing from an external class it will not work (the method was never called). My question is

What Changes do I need to make to my Listener class to make it call the method inside it

Following is the code : 

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var myView: UIView!

    override func viewDidLoad() {
        super.viewDidLoad()
        Listener(view : view , viewController: self).listen()
    }

    @objc func onNewTabArrived(){
        print("Hello from inside the controller")
    }

}


class Listener {
    let view : UIView
    let viewController: UIViewController

    init(view : UIView , viewController: UIViewController){
        self.view  = view
        self.viewController  = viewController
    }
    func listen(){
        // If you set the target as viewController it will call the method named onNewTabArrived inside it , printing "Hello from inside the controller"
        // let tab = UITapGestureRecognizer(target: viewController, action: #selector(onNewTabArrived))
        // view.addGestureRecognizer(tab)


        // This will not work! the text "Hello from inside Listener" will never be printed, How can I force it to be called ?.
         let tab = UITapGestureRecognizer(target: self, action: #selector(onNewTabArrived))
         view.addGestureRecognizer(tab)
    }

    @objc func onNewTabArrived(){
        print("Hello from inside Listener")
    }

}

Upvotes: 0

Views: 70

Answers (1)

Taras Chernyshenko
Taras Chernyshenko

Reputation: 2829

Your Listener object is deallocated right after you create it. Try to store it into property

@IBOutlet weak var myView: UIView!
var listener: Listener?
override func viewDidLoad() {
    super.viewDidLoad()
    self.listener = Listener(view : view , viewController: self)
    self.listener?.listen()
}

Upvotes: 2

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