Swift - UIAlertView - Bold text in message

I want to highlight some words in my UIAlertView message, either by making it bold, or, by underline.

let message = "This is normal text.\nBold Title:\n This is normal text"

let alert = UIAlertView(title: "Title", message: message, delegate: self, cancelButtonTitle: "Cancel", otherButtonTitles: "OK")

alert.show()

How could I make "Bold Title" bold (or underline) in message?

via Chebli Mohamed