How to assign a button’s action in code using @objc mark for given function?-CodePudding

Hi for this question I found answer on How to create a button programmatically? however still facing the errors: "Argument of '#selector' cannot refer to local function 'plusOne(sender:)'" and "@objc can only be used with members of classes, @objc protocols, and concrete extensions of classes". If you can advice.

let button = UIButton()
button.frame = CGRect(x: 150, y: 300, width: 60, height: 60)
button.setTitle("Click", for: .normal)
button.setTitleColor(UIColor.blue, for: .normal)
button.addTarget(self, action: #selector(plusOne), for: .touchUpInside)
self.view.addSubview(button)
    
@objc func plusOne(sender: UIButton!) {
    self.count  = 1 
    self.label.text = "\(self.count)"
}

CodePudding user response：

The problem you have is that you've nested the @objc func plusOne(sender: UIButton!) within viewDidLoad (which was why i asked the initial question about scope). You need to move it out to a class-scope method.

override func viewDidLoad() {
  // all the usual stuff...

  let button = UIButton()
  button.frame = CGRect(x: 150, y: 300, width: 60, height: 60)
  button.setTitle("Click", for: .normal)
  button.setTitleColor(UIColor.blue, for: .normal)
  button.addTarget(self, action: #selector(plusOne), for: .touchUpInside)
  self.view.addSubview(button)

}

@objc func plusOne(sender: UIButton!) {
    self.count  = 1 
    self.label.text = "\(self.count)"
}

CodePudding user response：

The name of the method is plusOne(sender:), the argument labels make part of the name