Creating UIButton programmatically in Swift 4 but getting error [duplicate] - swift

Question

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Expected declaration error for making high score [duplicate]
(2 answers)
Closed 4 years ago.
I'm trying to create a UIButton in Swift 4 but I keep getting a "Expected declaration" error in the "MyView" class when I try to call the addTarget function. I've done this same code in other classes and have never gotten the error. Am I missing something? Thanks.
import Foundation
import UIKit
protocol MyDelegate: class {
func onButtonTapped()
}
class OtherViewController: UIViewController {
}
class MyViewController: UIViewController, MyDelegate {
func onButtonTapped() {
let nextViewController = OtherViewController()
navigationController?.pushViewController(nextViewController, animated: false)
}
var myView: MyView!
override func viewDidLoad() {
super.viewDidLoad()
myView.delegate = self
}
}
class MyView: UIView {
weak var delegate: MyDelegate?
let button = UIButton()
button.addTarget(self, action: #selector(buttonTapped),for: .touchUpInside)
func buttonTapped() {
self.delegate?.onButtonTapped()
}
}

Answer 1

you cannot addTarget or call any method in the class space , this space is for declartion as the error suggests .
to fix this you can do either this
let button:UIButton =
{
let btn = UIButton()
btn.addTarget(self, action: #selector(buttonTapped),for: .touchUpInside)
return btn
}()
Or
let button:UIButton = UIButton()
override init(frame: CGRect) {
super.init(frame: frame)
button.addTarget(self, action: #selector(buttonTapped),for: .touchUpInside)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
in both cases you must add #objc annotation to the buttonTapped function because selectors must refer to an #objc function .
so it will be like this
#objc func buttonTapped(){}
Also you need to add this button to the view on order for it to be drawn to the screen .
view.addSubView(button)