I've made a very simple zero config category to hide all back button titles through out app you can check it out here. This question already has accepted answer, but for others it can be helpful.
EDIT:
.h file
#import <UIKit/UIKit.h>
@interface UINavigationController (HideBackTitle)
extern void PJSwizzleMethod(Class cls, SEL originalSelector, SEL swizzledSelector);
@end
.m file
#import "UINavigationController+HideBackTitle.h"
#import <objc/runtime.h>
@implementation UINavigationController (HideBackTitle)
+ (void)load {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
PJSwizzleMethod([self class],
@selector(pushViewController:animated:),
@selector(pj_pushViewController:animated:));
});
}
- (void)pj_pushViewController:(UIViewController *)viewController animated:(BOOL)animated {
UIViewController *disappearingViewController = self.viewControllers.lastObject;
if (disappearingViewController) {
disappearingViewController.navigationItem.backBarButtonItem=[[UIBarButtonItem alloc] initWithTitle:@"" style:UIBarButtonItemStylePlain target:nil action:nil];
}
if (!disappearingViewController) {
return [self pj_pushViewController:viewController animated:animated];
}
return [self pj_pushViewController:viewController animated:animated];
}
@end
void PJSwizzleMethod(Class cls, SEL originalSelector, SEL swizzledSelector)
{
Method originalMethod = class_getInstanceMethod(cls, originalSelector);
Method swizzledMethod = class_getInstanceMethod(cls, swizzledSelector);
BOOL didAddMethod =
class_addMethod(cls,
originalSelector,
method_getImplementation(swizzledMethod),
method_getTypeEncoding(swizzledMethod));
if (didAddMethod) {
class_replaceMethod(cls,
swizzledSelector,
method_getImplementation(originalMethod),
method_getTypeEncoding(originalMethod));
} else {
method_exchangeImplementations(originalMethod, swizzledMethod);
}
}