title: How can I get the opposite value of a Bool in Swift?
body: <p>My specific case is I am trying to toggle the nav bar hidden and showing.</p>
  
  <pre><code>    let navHidden = !self.navigationController?.navigationBarHidden
      self.navigationController?.setNavigationBarHidden(navHidden!, animated: true)
  </code></pre>
  
  <p>Is not working for me like it normally would in Obj-C.</p>