Reload BarButtonItem after pressing (Change formatted string title) - swift

Question

I have added a bar button item programmatically that will change the temperature units on some variables between Celsius and Fahrenheit and have set it with attributed text via a customView.
It is half Bold and half standard text. Whichever unit is selected will be bold.
After trying each method of refreshing them I would remove them after they didn't work. So in the code below there is no "reload/refresh" being attempted.
I have a boolean which changes when the action is called. However I cannot get the barButtomItem to "Reload/refresh" upon being selected.
I have debugged and the action is being called, the variable is changing, and the formatted text is being changed, however it is not changing on the screen.
//MARK: - Create Navigation Bar
func createNavBar() {
navigationController?.navigationBar.setBackgroundImage(UIImage(), for: .default)
navigationController?.navigationBar.shadowImage = UIImage()
navigationController?.navigationBar.backgroundColor = .clear
navigationController?.navigationBar.isTranslucent = true
let CFLabel = UILabel()
CFLabel.attributedText = formatCFButton()
CFLabel.sizeToFit()
CFLabel.isUserInteractionEnabled = true
let tap = UITapGestureRecognizer(target: self, action: #selector(CFChanger))
CFLabel.addGestureRecognizer(tap)
let CFButton = UIBarButtonItem.init(customView: CFLabel)
let addCityButton = UIBarButtonItem.init(barButtonSystemItem: .add, target: self, action: #selector(addCity))
addCityButton.tintColor = .black
self.navigationItem.rightBarButtonItem = addCityButton
self.navigationItem.leftBarButtonItem = CFButton
}
#objc func CFChanger() {
print("CF BUTTON PRESSED AND FUNCTION ACTIVATED!")
isCelsius = !isCelsius
}
//Change font(bold) change temperature units button
func formatCFButton() -> NSMutableAttributedString {
let changeTempString = NSMutableAttributedString()
let boldAttribute = [NSAttributedString.Key.font: UIFont(name: "HelveticaNeue-Bold", size: 18.0)!]
let regularAttribute = [NSAttributedString.Key.font: UIFont(name: "HelveticaNeue-Light", size: 18.0)!]
if isCelsius == true {
let boldText = NSAttributedString(string: "C ", attributes: boldAttribute)
let regularText = NSAttributedString(string: "/ F", attributes: regularAttribute)
changeTempString.append(boldText)
changeTempString.append(regularText)
} else {
let boldText = NSAttributedString(string: "F ", attributes: boldAttribute)
let regularText = NSAttributedString(string: "C / ", attributes: regularAttribute)
changeTempString.append(regularText)
changeTempString.append(boldText)
}
return changeTempString
}
I was able to get this to work in the past when I did NOT create the button programmatically by adding this code into the function when the button is pressed. I am not sure how to do this programmatically. (sender stuff)
// MARK: - Change units function
//****************************************************************************
#IBAction func changeUnitsButtonPressed(_ sender: UIButton) {
isCelsius = !isCelsius
var tempUnitNumber = 0
if isCelsius == true {
tempUnitNumber = 1
} else {
tempUnitNumber = 2
}
defaults.set(tempUnitNumber, forKey: "tempUnit")
let changeTempString = formatCFButton()
sender.setAttributedTitle(changeTempString, for: [])
tableView.reloadData()
}