UINavigationItem+KZAdditions.h

@import UIKit;

@interface UINavigationItem (KZAdditions)

@property (nonatomic, copy) NSDictionary *kz_titleTextAttributes;

@end

UINavigationItem+KZAdditions.m

#import "UINavigationItem+KZAdditions.h"
#import "Aspects.h"

@import ObjectiveC.runtime;

static void const *TitleTextAttributesKey = &TitleTextAttributesKey;
@implementation UINavigationItem (UGCAdditions)

- (NSDictionary *)kz_titleTextAttributes;
{
    return objc_getAssociatedObject(self, TitleTextAttributesKey);
}

- (void)setKz_titleTextAttributes:(NSDictionary *)titleTextAttributes;
{
    objc_setAssociatedObject(self, TitleTextAttributesKey, titleTextAttributes, OBJC_ASSOCIATION_COPY_NONATOMIC);
}

@end

__attribute__((constructor)) static void __load()
{
    void (^setAttributes)(id, UIViewController *) = ^(id target, UIViewController *vc) {
        NSCParameterAssert([target isKindOfClass:UINavigationController.class]);
        UINavigationController *navigationController = target;
        navigationController.navigationBar.titleTextAttributes = vc.navigationItem.kz_titleTextAttributes;
    };
    
    [UINavigationController aspect_hookSelector:@selector(pushViewController:animated:) withOptions:AspectPositionBefore usingBlock:^(id <AspectInfo> info, UIViewController *vc, BOOL _) {
        setAttributes(info.instance, vc);
    } error:nil];
    
    [UINavigationController aspect_hookSelector:@selector(popViewControllerAnimated:) withOptions:AspectPositionBefore usingBlock:^(id <AspectInfo> info, BOOL _) {
        UINavigationController *navigationController = (UINavigationController *)info.instance;
        int index = (int)(navigationController.viewControllers.count - 2);
        if (index >= 0) {
            UIViewController *vc = navigationController.viewControllers[index];
            setAttributes(navigationController, vc);
        }
    } error:nil];
    
    [UINavigationController aspect_hookSelector:@selector(popToRootViewControllerAnimated:) withOptions:AspectPositionBefore usingBlock:^(id <AspectInfo> info, BOOL _) {
        UINavigationController *navigationController = (UINavigationController *)info.instance;
        setAttributes(navigationController, navigationController.viewControllers.firstObject);
    } error:nil];
    
    [UINavigationController aspect_hookSelector:@selector(popToViewController:animated:) withOptions:AspectPositionBefore usingBlock:^(id <AspectInfo> info, UIViewController *vc, BOOL _) {
        setAttributes(info.instance, vc);
    } error:nil];
    
    [UINavigationController aspect_hookSelector:@selector(setViewControllers:animated:) withOptions:AspectPositionBefore usingBlock:^(id <AspectInfo> info, NSArray *viewControllers, BOOL _) {
        int index = (int)(viewControllers.count - 1);
        if (index >= 0) {
            setAttributes(info.instance, viewControllers[index]);
        }
    } error:nil];
}