title: ios/xcode: change title of bar button item
body: <p>I want to change the title of a bar button (right navigation) from login to sign up depending on which the user checks.</p>
  
  <p>Previously, I had this as a button in the VC and it worked with the following code:</p>
  
  <pre><code>[_submitButton setTitle:@"Sign Up" forState:UIControlStateNormal];
  </code></pre>
  
  <p>However, now that I've deleted the button in the page and have given the bar button the name submitButton, I am getting the following error:</p>
  
  <p>No visible @interface for 'UIBarButtonItem' declares the selector 'setTitleForState'</p>
  
  <p>Does anyone know why this is not working?  Do I have to name uibarbutton something different than a regular button?</p>