How to call / access a label in button action programmatically? - ios

Question

//This is the label
let changeLbl = UILabel(frame: CGRect(x: 20, y: 170, width: 300, height: 21))
self.view.addSubview(changeLbl)
//This is the button
let submitButton = UIButton(type: .system) // let preferred over var here
submitButton.addTarget(self, action: #selector(buttonAction) , for: UIControlEvents.touchUpInside)
self.view.addSubview(submitButton)
//and this is action of above button
func buttonAction(sender: UIButton!) {
}
I want to call the above label in the following button function? like
func buttonAction(sender: UIButton!) {
changeLbl.ishidden = true
// want to access label here, but it's not working this way.
}

Answer 1

If you want to Access changeLbl you need to define as instance variable like this way and give global scope inside the class.
class ViewController: UIViewController {
var changeLbl : UILabel!
var submitButton : UIButton!
override func viewDidLoad() {
super.viewDidLoad()
//This is the UILabel
changeLbl = UILabel(frame: CGRect(x: 20, y: 170, width: 300, height: 21))
self.view.addSubview(changeLbl)
//This is the button
submitButton = UIButton(type: .system) // let preferred over var here
submitButton.addTarget(self, action: #selector(buttonAction) , for: UIControlEvents.touchUpInside)
self.view.addSubview(submitButton)
}
//and this is action of above button
func buttonAction(sender: UIButton!) {
changeLbl.isHidden = true
}
}

Answer 2

changeLbl is a local variable. It's only visible in the scope of the method where the label is created.
If you don't want to use an instance variable – which is the normal way – and there is only one UILabel you can get the label from the subviews array
func buttonAction(sender: UIButton) {
if let changeLbl = self.view.subviews.filter({ $0 is UILabel}).first {
changeLbl.ishidden = true
}
}

Answer 3

If You want access label then declare it Globally.
Below Code for that:
class LabelDemo: UIViewController{
var changeLbl: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
changeLbl = UILabel(frame: CGRect(x: 20, y: 170, width: 300, height: 21))
changeLbl.backgroundColor = UIColor.black
self.view.addSubview(changeLbl)
//This is the button
let submitButton = UIButton(type: .system) // let preferred over var here
submitButton.backgroundColor = UIColor.green
submitButton.frame = CGRect(x: 50, y: 150, width: 50, height: 30)
submitButton.setTitle("hide", for: .normal)
submitButton.addTarget(self, action: #selector(buttonAction) , for: UIControlEvents.touchUpInside)
self.view.addSubview(submitButton)
}
func buttonAction(sender: UIButton!) {
if changeLbl.isHidden {
changeLbl.isHidden = false
}else{
changeLbl.isHidden = true
}
}
}