#selector(didTapRegister) not in scope - swift

Question

When I run this code by #selector(didTapRegister) I get a didTapRegister is not in scope. I have a bigger application I am using it in and on one page it works and another it won't, well it won't work anywhere else.
I am stuck on figuring out why. Can anyone help solve it? seems to be an Objective-C issue possibly because I have same issues trying to make IBOutlets, I have tried searching for answers and I just don't have enough knowledge to understand why it isn't working, I've tried moving the code to different scopes and still nothing. with the IBOutlets it's saying IBOutlet property cannot have non-object type UIButton?.Type
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let Button = UIButton.init(type: .custom)
Button.setTitle("Chat", for: .normal)
Button.layer.backgroundColor = CGColor.init(gray: 0.0, alpha: 0.0)
Button.setTitleColor(.white, for: .normal)
Button.setTitleColor(.red, for: .highlighted)
Button.layer.borderWidth = 1
Button.layer.cornerRadius = 5
Button.layer.borderColor = UIColor.white.cgColor
Button.isHighlighted = false
Button.showsTouchWhenHighlighted = true
self.navigationItem.rightBarButtonItem = UIBarButtonItem(customView: Button)
Button.addTarget(self, action: #selector(didTapRegister), for: .touchUpInside)
navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)
navigationController?.navigationBar.shadowImage = UIImage()
navigationController?.navigationBar.isTranslucent = true
func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
// Do any additional setup after loading the view.
}
}
}

Answer 1

Maybe try what he said but
Just use SwiftUI it is much better
#objc and all of that is fine but in SwiftUI you can just right click and add buttons

Answer 2

There 2 mistakes in the code.
You have to create #objc function for the button action
In your code move viewWillAppear method outside the viewDidLoad
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let button = UIButton.init(type: .custom)
button.setTitle("Chat", for: .normal)
button.setTitleColor(.white, for: .normal)
button.setTitleColor(.red, for: .highlighted)
button.layer.borderWidth = 1
button.layer.cornerRadius = 5
button.layer.borderColor = UIColor.white.cgColor
button.isHighlighted = false
button.showsTouchWhenHighlighted = true
self.navigationItem.rightBarButtonItem = UIBarButtonItem(customView: button)
button.addTarget(self, action: #selector(didTapRegister), for: .touchUpInside)
navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)
navigationController?.navigationBar.shadowImage = UIImage()
navigationController?.navigationBar.isTranslucent = true
}
#objc func didTapRegister(_ sender: UIButton) {
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
// Do any additional setup after loading the view.
}
}
Note: button name start with lowercase.