gistfile1.m

@implementation JWNavigationController

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated;
{
    if (viewController.navigationItem.leftBarButtonItem == nil)
    {
        JKBackBarButtonItem *backItem = [[JWBackBarButtonItem alloc] initWithTitle:self.topViewController.navigationItem.title ?: @"Back"
                                                                              target:self
                                                                              action:@selector(doPop:)];
        viewController.navigationItem.leftBarButtonItem = backItem;
    }
    [super pushViewController:viewController animated:animated];
}

- (void)doPop:(id)sender;
{
    [self popViewControllerAnimated:YES];
}

@end