swift how change UIAlertController font - swift

Question

When I added an extension to UIAlertController to modify actions fonts, it didn't seem to work. What should I do to modify the Action font。
Here is my code
extension UIAlertController {
open override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
if self.preferredStyle == .actionSheet {
for i in self.actions {
let attributedText = NSAttributedString(string: i.title ?? "", attributes: [NSAttributedString.Key.font : UIFont(name: "SFProText-Semibold", size: 15.0)!])
guard let label = (i.value(forKey: "__representer") as AnyObject).value(forKey: "label") as? UILabel else { return }
label.attributedText = attributedText
}
}
}
}

Answer 1

Create an extension of UIAlertController
extension UIAlertController {
func setBackgroudColor(color: UIColor) {
if let bgView = self.view.subviews.first,
let groupView = bgView.subviews.first,
let contentView = groupView.subviews.first {
contentView.backgroundColor = color
}
}
func setTitle(font: UIFont?, color: UIColor?) {
guard let title = self.title else { return }
let attributeString = NSMutableAttributedString(string: title)
if let titleFont = font {
attributeString.addAttributes([NSAttributedString.Key.font : titleFont],
range: NSMakeRange(0, title.utf8.count))
}
if let titleColor = color {
attributeString.addAttributes([NSAttributedString.Key.foregroundColor : titleColor],
range: NSMakeRange(0, title.utf8.count))
}
self.setValue(attributeString, forKey: "attributedTitle")
}
func setMessage(font: UIFont?, color: UIColor?) {
guard let title = self.message else {
return
}
let attributedString = NSMutableAttributedString(string: title)
if let titleFont = font {
attributedString.addAttributes([NSAttributedString.Key.font : titleFont], range: NSMakeRange(0, title.utf8.count))
}
if let titleColor = color {
attributedString.addAttributes([NSAttributedString.Key.foregroundColor : titleColor], range: NSMakeRange(0, title.utf8.count))
}
self.setValue(attributedString, forKey: "attributedMessage")
}
func setTint(color: UIColor) {
self.view.tintColor = color
}
}
Call it from a UIViewController may be in a button action like below.
func tapShowAlert() {
let alertController = UIAlertController(title: "Alert!!", message: "This is custom alert message", preferredStyle: .alert)
alertController.setTitle(font: UIFont.boldSystemFont(ofSize: 24), color: UIColor.yellow)
alertController.setMessage(font: UIFont(name: "Verdana", size: 16), color: UIColor.red)
let actnOk = UIAlertAction(title: "Ok", style: .default, handler: nil)
let actnCancel = UIAlertAction(title: "Cancel", style: .default, handler: nil)
alertController.addAction(actnOk)
alertController.addAction(actnCancel)
self.present(alertController, animated: true, completion: nil)
}