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When using a Navigation Controller in a Cocoa Touch application, the framework takes care of many things, including generation of a back button when you push a view controller to the navigation controller. The back button gets the same title of the parent view, which a lot of the time is what you might want, but every now and again it's not. For example, in my cool application, the initial view has the title 'My Cool Application' - when you navigate to the settings view, the back button has the long, unwieldy title 'My Cool Application', making the button so big that it pushes the 'Settings' title to the right.

Manually setting the title of the back button by messing with navigationItem.backBarButtonItem doesn't work. However, you can set the leftBarButtonItem property of the second view to a button that you create yourself, which suppresses the navigation controller from automatically creating a button. You can set the title of your button to whatever you want, but how do you get an arrow button like the automatically generated one?

I've seen some people take the approach of using an image. I prefer using an undocumented button type, 101. Adding the code below to the constructor of my settings view controller changes the horrible big back button into a small button with the title 'Back':

- (id) initWithNibName:(NSString*)nibNameOrNil bundle:(NSBundle*)nibBundleOrNil {  
  self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];  
  if (self) {  
      UIButton* customBackButton = [UIButton buttonWithType:101];  
      [customBackButton setTitle:@"Back" forState:UIControlStateNormal];  
      [customBackButton addTarget:self  
        action:@selector(done) forControlEvents:UIControlEventTouchUpInside];  
      myBackButton = [[UIBarButtonItem alloc] initWithCustomView:customBackButton];  
      [self.navigationItem setLeftBarButtonItem:myBackButton];  
  }  
  return self;  
}  

The myBackButton instance variable is defined as: UIBarButtonItem* myBackButton. The action taken when the button is pressed is defined in a method I've called done.

Yep, that's much better!

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Posted Sat 21 May 2011 by Michael Patricios

Tags: Development, iOS, Objective-C