title: Can we disabled the navigation controller of leftBarButtonItem that is back button of the view controller in iPhone?
body: <p>I want to disabled the default back button of navigation controller </p>
  
  <pre><code>self.navigationItem.rightBarButtonItem.enabled = NO; 
  // Below code does not work since leftBarButtonItem is always nil.
  self.navigationItem.leftBarButtonItem.enabled = NO;
  </code></pre>
  
  <p>I have done it with manually shown below, But Is there any property to disabled the default back button with just single line?</p>
  
  <pre><code>backButton = [[UIButton alloc] initWithFrame:CGRectMake(5, 5, 100, 30)];
  [backButton setBackgroundImage:[UIImage imageNamed:@"backbutton_100.png"] forState:UIControlStateNormal];
  [backButton addTarget:self  action:@selector(backAction:)  forControlEvents:UIControlEventTouchUpInside];
  [backButton setTitle:@"  All Customers" forState:UIControlStateNormal];
  backButton.titleLabel.font = [UIFont boldSystemFontOfSize:12];
  [buttonView addSubview:backButton];
  
  UIBarButtonItem* leftButton = [[UIBarButtonItem alloc] initWithCustomView:buttonView];
  self.navigationItem.leftBarButtonItem = leftButton;
  [leftButton release];
  
  // Now it is working.
  self.navigationItem.leftBarButtonItem.enabled = NO;
  </code></pre>