Change font of back navigation bar button

Question

I want to be able to set the font of my apps navigation bar back button without doing anything too crazy and without losing any other design characteristics of the button (i.e. I want to keep the arrow).

Right now I use this in viewDidAppear: to set the font of the normal bar button items.

for (NSObject *view in self.navigationController.navigationBar.subviews) {
    if ([view isKindOfClass:[UIButton class]]) {
        [((UIButton*)view).titleLabel setFont:[UIFont 
                                 fontWithName:@"Gill Sans" 
                                         size:14.0]];
    }
}

However this makes no change on the back button, regardless of which UIViewController this code is applied to (root, current, etc.).

Answer 1

To change the appearance of the text in all UIBarButtonItems appearing in all UINavigationBars, do the following in application:didFinishLaunchingWithOptions:

[[UIBarButtonItem appearanceWhenContainedIn:[UINavigationBar class], nil] setTitleTextAttributes:
    @{UITextAttributeTextColor:[UIColor blackColor],
     UITextAttributeTextShadowOffset:[NSValue valueWithUIOffset:UIOffsetMake(0, 1)],
     UITextAttributeTextShadowColor:[UIColor whiteColor],
     UITextAttributeFont:[UIFont boldSystemFontOfSize:12.0]
    }
     forState:UIControlStateNormal];

UPDATE: iOS7 friendly version

NSShadow *shadow = [[NSShadow alloc] init];
shadow.shadowOffset = CGSizeMake(0.0, 1.0);
shadow.shadowColor = [UIColor whiteColor];

[[UIBarButtonItem appearanceWhenContainedIn:[UINavigationBar class], nil]
 setTitleTextAttributes:
 @{NSForegroundColorAttributeName:[UIColor blackColor],
   NSShadowAttributeName:shadow,
   NSFontAttributeName:[UIFont boldSystemFontOfSize:12.0]
   }
 forState:UIControlStateNormal];

Swift:

NOTE: this changes ALL instances of UIBarButtonItem, not just those contained within a UINavigationBar

UIBarButtonItem.appearance()
               .setTitleTextAttributes([NSFontAttributeName : ExamplesDefaults.fontWithSize(22)], 
                                       forState: UIControlState.Normal)

Swift3:

UIBarButtonItem.appearance()
     .setTitleTextAttributes([NSFontAttributeName: UIFont(name: "FontName-Regular", size: 14.0)!], 
                             for: .normal)