How to customize back button on UINavigationBar

Sometimes, we need to change the back button's image on UINavigationBar. Many articles introduce a method in which you need to change the back button in the corresponding view controller.

for example:

Assuming you have a view controller called TestViewController controlled by the UINavigationController, then you can set the back button in the viewDidLoad  method

 

-(void) viewDidLoad { UIImage *btnImage = [UIImage imageNamed:@"Back.png"]; UIImage *btnImageSelected = [UIImage imageNamed:@"BackPressed.png"]; UIButton* btn = [UIButton buttonWithType:UIButtonTypeCustom]; btn.titleLabel.font = [UIFont systemFontOfSize:12]; [btn setTitle:btntitle forState:UIControlStateNormal]; btn.frame = CGRectMake(0, 0, 63, 32); [btn setBackgroundImage:btnImage forState:UIControlStateNormal]; [btn setBackgroundImage:btnImageSelected forState:UIControlStateSelected]; [btn addTarget:self action:@selector(handleBack:) forControlEvents:UIControlEventTouchUpInside]; UIBarButtonItem* backItem = [[UIBarButtonItem alloc]initWithCustomView:btn]; self.navigationItem.leftBarButtonItem = backItem; [backItem release] } 

then you still need to add event handle:

- (void) handleBack:(id)sender { [self.navController popViewControllerAnimated:YES]; } 

 

But, if you have multiple view controllers, you have to add the above code in each controller. so to reuse the code, I try to subclass the UINavigationController and try to customize the back button in the pushViewController method.

for example:

-(UIBarButtonItem*) createBackButton:(NSString*) btntitle { ...... //as the above button creation code } - (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated { [super pushViewController:viewController animated:animated]; if (viewController.navigationItem.leftBarButtonItem == nil) { NSString* backButtonTitle = self.navigationBar.backItem.title; viewController.navigationItem.leftBarButtonItem = [self createBackButton:backButtonTitle]; } } 

 

More explaining on this method, you have to create a new back button for each viewController. if you reuse one button 

for each view controller, there will be some display problem-- some view controller's button may not be displayed, I'm

not very clear about it now.