title: set title of back bar button item in ios
body: <p>I am using storyboards in my application, and if I set the title property of a ViewController class, that string will appear as the text of my back button when I push a SecondViewController, how can I change this?, I want to put a different title for the back button.</p>
  
  <p>I have used this but it doesn't work:</p>
  
  <pre><code>UIBarButtonItem *btnBack = [[UIBarButtonItem alloc]
                                     initWithTitle:@"Back" 
                                     style:UIBarButtonItemStyleBordered
                                     target:self
                                     action:nil];
      [self.navigationItem setBackBarButtonItem: btnBack];
  </code></pre>
  
  <p>please help me</p>