Why use tags with UIButtons? – Ios swift

As others have said the function could be completely independent of the button, it could be in another class altogether.

Buttons may not be in StoryBoards and could be created programatically, potentially dynamically, so there maybe no case of checking if the button passed to the function is the same as a local variable (as a button may not be an ivar on the class the function is based on)

Tags give an easy way to provide some identifier to button or view that can be cross referenced when the function is called in order to achieve the desired out come

Here’s an example to illustrate, bear in mind this is somewhat contrived in order to provide an detail

In you ViewController you need to dynamically create a button but don’t want to store it as a variable on the VC. You also have a separate class which is handling taps

We could create an enum to handle button types, this handles the tag and title for the button type

enum ButtonType: String {
    case nonIvar
    case other
    
    var tag: Int  {
        switch self {
        case .nonIvar:
            return 0
        case .other:
            return 1
        }
    }
    
    var title: String {
        switch self {
        case .nonIvar:
            return "Non iVar Button"
        case .other:
            return "Some other Button"
        }
    }
}

we then have our class that handles the tap function

class ButtonHandler {
    @IBAction func handleTap(_ sender: UIButton) {
        if sender.tag == ButtonType.nonIvar.tag {
            // do something with the none ivar buton
        } else {
            // handle other type
        }
    }
}

then in our view controller we create our button hooking the two instances above up

let handler = ButtonHandler()
func addMyButton() {
let myButton = UIButton(frame: CGRect(x: 0, y: 0, width: 50, height: 50))
let buttonType: ButtonType = .nonIvar
myButton.setTitle(buttonType.title, for: .normal)
myButton.tag = buttonType.tag
myButton.addTarget(self, action: #selector(handler.handleTap(_:)), for: .touchUpInside)
view.addSubview(myButton)
}

This means that the handler can be used on any class and the button types could be equally used throughout the app and the behaviour would be the same without duplicating code

Hope this helps!