UIButton addTarget Selector 不工作

Question

SquareBox.swift

class SquareBox {
  func createBoxes() {
    for _ in 0..<xy {
            let button = UIButton()

            button.backgroundColor = .white
            button.setTitleColor(UIColor.black, for: .normal)
            button.layer.borderWidth = 0.5
            button.layer.borderColor = UIColor.black.cgColor
            stack.addArrangedSubview(button)
            button.addTarget(self, action: #selector(click(sender:)) , for: .touchUpInside)
    }
  }

  @objc func click(sender : UIButton) {
    print("Click")
  }
}

ViewController.swift

class GameViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        let boxRow = SquareBox() 
        boxRow.createBoxes()
    }
}

Also I've tried @IBAction instead of @objc, it doesn't work, but if I use "click" function in ViewController.swift that I created this object, it's working but I need this function inside of this class.

Answer 1

Now that you have posted relevant information in your question, the problem is quite clear. You have a memory management issue.

In your GameViewController's viewDidLoad you create a local instance of SquareBox . This local instance goes out of scope at the end of viewDidLoad . Since there is no other reference to this instance, it gets deallocated at the end of viewDidLoad .

Since the instance of SquareBox has been deallocated, it is not around to act as the button's target. And your click method is never called.

The solution is to keep a reference in your view controller:

class GameViewController: UIViewController {
    let boxRow = SquareBox() 

    override func viewDidLoad() {
        super.viewDidLoad()
        boxRow.createBoxes()
    }
}

Answer 2

 var btnfirst:UIButton!
 override func viewDidLoad() 
 {
    super.viewDidLoad()
    btnfirst = UIButton(type: .system)
    btnfirst.setTitle("Press", for: .normal)
    btnfirst.setTitleColor(.red, for: .normal)
    btnfirst.frame = CGRect(x: 100, y: 200, width: 100, height: 30)
    btnfirst.addTarget(self, action: #selector(benpress( sender:)),for: .touchUpInside)
    self.view.addSubview(btnfirst)
}

func benpress( sender :UIButton) 
{
  //Your Code Here                       
}

Answer 3

For those who did not find a solution, here is mine.

If you constructed your UIButton as

let button: UIButton = {
  return UIButton()
}()

Just convert those into

lazy var button: UIButton = {
  return UIButton()
}()

I think this is because of somewhat deallocation as mentioned above.

Answer 4

button.addTarget(self, action:#selector(self.click), for: .touchUpInside)

func click(sender : UIButton) {
       // code here
    }

Answer 5

I guess the issue is how you are setting up layout of your buttons. Try this:

func createBoxes() {
    stack.backgroundColor = UIColor.red
    for _ in 0..<xy {
        // Create the button
        let button = UIButton()
        button.backgroundColor = UIColor.red

        // Add constraints
        button.translatesAutoresizingMaskIntoConstraints = false
        button.heightAnchor.constraint(equalToConstant: 44.0).isActive = true
        button.widthAnchor.constraint(equalToConstant: 44.0).isActive = true

        // Setup the button action
        button.addTarget(self, action: #selector(SquareBox.click(sender:)), for: .touchUpInside)

        // Add the button to the stack
        stack.addArrangedSubview(button)
    }
}

@objc func click(sender : UIButton) {
    print("Click")
}

Answer 6

button.addTarget(self, action: #selector(self.buttonTapped), for: .touchUpInside)

func buttonTapped(sender : UIButton) {
       // code here
    }

Answer 7

Replace with this:

    btn.addTarget(self, action: #selector(self.click(sender:)), for: .touchUpInside)

I think something else effect to your selector method try to find in your code because your code also working in my project.