Add a string property to a UIButton in Swift - ios

Question

How can I associate a string property with a UIButton in Swift? I don't want the string to appear as the button text, simply to be assigned to the button as an identifier or a key. Here is what I have so far:
func createAnswerButtons() {
var index:Int
for index = 0; index < self.currentQuestion?.answers.count; index++ {
// Create an answer button view
var answer:AnswerButtonView = AnswerButtonView()
selection.setTranslatesAutoresizingMaskIntoConstraints(false)
// Place into content view
self.scrollViewContentView.addSubview(answer)
// Add a tapped gesture recognizer to the button
let tapGesture:UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: Selector("answerTapped:"))
answer.addGestureRecognizer(tapGesture)
// Add constraints etc
// Set the answer button text
let answerText = self.currentQuestion!.answers[index]
answer.setAnswerText(answerText)
// Set the identifier for each answer button
self.identifier = self.currentQuestion!.answerIdentifier[index]
// Add to the selection button array
self.answerButtonArray.append(answer)
}
So I think I need something after
// Set the identifier for each answer
self.identifier = self.currentQuestion!.answerIdentifier[index]
To assign the identifier to the button.
The reason for this is I'm trying to implement a decision tree logic so that I can keep track of each answer button that is tapped to generate a code string that will correspond to a final result.

Answer 1

Using the Objective-C runtime, we can add properties to classes at runtime:
extension UIButton {
private struct AssociatedKeys {
static var DescriptiveName = "nsh_DescriptiveName"
}
#IBInspectable var descriptiveName: String? {
get {
return objc_getAssociatedObject(self, &AssociatedKeys.DescriptiveName) as? String
}
set {
if let newValue = newValue {
objc_setAssociatedObject(
self,
&AssociatedKeys.DescriptiveName,
newValue as NSString?,
UInt(OBJC_ASSOCIATION_RETAIN_NONATOMIC)
)
}
}
}
}
Adding #IBInspectable also lets us set the descriptiveName property through Interface Builder.
For more about the Objective-C runtime, I recommend you check out this NSHipster article.

Answer 2

You can use the accessibility identifier (button.accessibilityIdentifier), if the button you want to identify should have a unique identifier (this matters if you're ever writing UI tests).
You can also subclass UIButton and add a variable buttonIdentifier.
class IdentifiedButton: UIButton {
var buttonIdentifier: String?
}

Answer 3

You can use accessibilityIdentifier property of UIButton.
#IBOutlet weak var button: UIButton!
button.accessibilityIdentifier = "Some useful text"

Answer 4

Use
button.accessibilityIdentifier = "some text"
istead of tag.

Answer 5

You can create an array with the strings you want associated with the button. Then set the buttons tag to the index of the string you want associated with the button. Hence:
var myStrings = ["First","Second","Third"]
button.tag = //insert a number corresponding to the string index in myStrings that you want for the button
func buttonPressed(sender: UIButton){
var selectedString = myString[sender.tag]
}