Could not execute a function on UITapGestureRecognizer - iphone

Question

Whenever i touch on the screen nothing happens. looks like handleDismiss() function is never fired. Does anybody knows what is the real problem here.
import UIKit
class SettingLauncher : NSObject{
let blackView = UIView();
func showSettingMenu(){
if let window = UIApplication.shared.keyWindow{
blackView.backgroundColor = UIColor(white: 0, alpha: 0.5);
blackView.isUserInteractionEnabled = true;
blackView.addGestureRecognizer(UITapGestureRecognizer(target: nil, action: #selector(self.handleDismiss)));
window.addSubview(blackView);
blackView.frame = window.frame;
blackView.alpha = 0.1;
UIView.animate(withDuration: 0.5) {
self.blackView.alpha = 0.5;
}
}
}
func handleDismiss(){
print("Touch recognised");
}
}

Answer 1

You have to tell the UITapGestureRecognizer which class will be handling the response - not just which function, but which class
Change
blackView.addGestureRecognizer(UITapGestureRecognizer(target: nil, action: #selector(self.handleDismiss)));
To
blackView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(self.handleDismiss)))
Here's an example which I have working. I am initiating the view from a button - I don't know how yours is started, but that shouldn't matter
class ViewController: UIViewController
{
let blackView = UIView()
override func viewDidLoad()
{
super.viewDidLoad()
}
func handleDismiss(){
print("Touch recognised");
}
#IBAction func cmdDoOtherStuff(_ sender: Any)
{
if let window = UIApplication.shared.keyWindow{
blackView.backgroundColor = UIColor(red: 1.0, green: 0, blue: 0, alpha: 0.5)//(r: 0, alpha: 0.5)
blackView.isUserInteractionEnabled = true
blackView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(self.handleDismiss)))
window.addSubview(blackView)
blackView.frame = window.frame
blackView.alpha = 0.1
UIView.animate(withDuration: 0.5) {
self.blackView.alpha = 0.5;
}
}
}
}

Answer 2

I got the above error because I called the function showSettingMenu() through another class function as below:-
func handleMoreSetting(){
let settingLauncher = SettingLauncher();
settingLauncher.showSettingMenu(); // Call SettingLauncher class
}
The problem went away when I declared settingLauncher as global instance like below.
let settingLauncher = SettingLauncher();
func handleMoreSetting(){
settingLauncher.showSettingMenu(); // Call SettingLauncher class
}
Do anybody knows why the problem occured? In both cases, I am calling the same function but with a different result.