Change UIAlertController message or title during its presentation

this is possible of course, please check the following:

class MyViewController:  UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let alertController = UIAlertController(title: "My Title", message: "My Message", preferredStyle: .alert)

        present(alertController, animated: true, completion: nil)

        // Do your queries and get your new title and then set the new title
        alertController.title = "Your new title"
    }

}

It is possible to change the title and/or text AND animate the change, thusly:

[UIView transitionWithView: alertController.view
                  duration: 0.3
                   options: UIViewAnimationOptionTransitionCrossDissolve
                animations: ^(void) {
                    alertController.message = newMessage;
                }
                completion: nil];

Or in Swift:

UIView.transition(with: alertController.view,
                  duration: 0.3,
                  options: .transitionCrossDissolve,
                  animations: { alertController.message = newMessage }
)