title: Add subtitle under the title in navigation bar controller in Xcode
body: <p>So I'm wanting to add a "subtitle" under the title in the navigation bar in navigation controller.</p>
  
  <p>Mostly everything I look up so far wants me to use CGRect. I don't know a whole lot what that is and it sounds like its wanting me to create an entire new view which is not what I am wanting to do.</p>
  
  <p>My question is, is there a dot method to adding a subtitle view easily?</p>
  
  <p>The closest thing I found was posted on stack overflow and here is the link:</p>
  
  <p><a href="https://stackoverflow.com/questions/29626710/create-a-subtitle-in-navigationbar">Create a subtitle in navigationbar</a></p>
  
  <p>Apparently last year this worked but now I am getting errors and it's in my viewDidLoad...</p>
  
  <p>I tried this:</p>
  
  <p>self.navigationController?.navigationItem.prompt = "Subtitle Here"</p>
  
  <p>It's the only thing that won't show any errors but still doesn't work. It literally does nothing. At least nothing visible at run time.</p>
  
  <p>On a side note, swift is preferred. Thanks!</p>