title: Change rightBarButtonItems Title
body: <p>How can I change the title of the buttons on my <strong>rightbarButtonItems</strong>?</p>
  
  <p>I have multiple buttons on the right side of the navigation bar, though I can change a button's title if there is only one rightbarButton but for multiple I can't.</p>
  
  <pre><code>doneButton = [[UIBarButtonItem alloc]
  initWithTitle:@"Done"
  style:UIBarButtonSystemItemDone target:self action:@selector(doneTouch)];
  editButton = [[UIBarButtonItem alloc]
  initWithTitle:@"Edit"
  style:UIBarButtonItemStylePlain
  target:self action:@selector(Edit:)];
  NSArray *myButtonArray = [[NSArray alloc] initWithObjects:doneButton,editButton,nil];
  [self.navigationItem setRightBarButtonItems:myButtonArray];
  </code></pre>
  
  <p>I want to change the title of the <strong>editButton</strong> but I can't using:</p>
  
  <pre><code>[self.editButtonItem setTitle:@"Done"];
  </code></pre>