Here are listed some of the functionalities that can be implemented on navigationBar:-

The below code will Hide the back button from NavigationBar :-

self.navigationItem.hidesBackButton = YES;

Thie below code will Set background image to the navigationBar.. This can be implemented by adding the code in AppDelegate method as following :-

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

 [[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:@"top_baar_image] forBarMetrics:UIBarMetricsDefault];
   
    return YES;
}

To add a UIButton programatically to navigationBar and also set its TextColor :-

UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:@Button_Title style:UIBarButtonItemStylePlain target:self action:@selector(back:)];
    
self.navigationItem.rightBarButtonItem=backButton;

  [backButton setTintColor:[UIColor redColor]];

 Define the selector method :-

-(void)back:(UIBarButtonItem *)sender {
   NSLog(@"Your code for button action");
    
}

The below code will remove the back navigation title :-

self.navigationController.navigationBar.topItem.title = @"";

Set the title of navigationItem :-

self.navigationItem.title = @"The title";

Thie below code will Change the background color of navigationBar :-

navigationController.navigationBar.barTintColor = [UIColor greenColor];