objective c - Custom navigationItem button with QLPreviewController in iOS6

Question

my goal is to use QLPreviewController in my iPad application for iOS6, using my custom Action item button in the top toolbar. I had solution until iOS5.1. I used a class that extends QLPreviewController and during component lifecycle I did something like

[[self navigationItem] setRightBarButtonItems:[NSArray arrayWithObject:[self buildCustomButton]]];

With iOS6 this trick doesn't work more, and now it seems impossible change navigationItem configuration. I think that introduction of UIActivity and Social Framework could be involved and maybe it's no more effective to work on navigationItem, but I can find any solution. Any suggestion? Thanks, bye

Answer 1

I really really needed a solution, so I made this up.

Yes, it's ugly. Yes, it may break at any time. And yes, I'll go strait to dev hell, but my boss did stop stare at me with angry eyes...for now.

@implementation UINavigationItem (Custom)

void MethodSwizzle(Class c, SEL origSEL, SEL overrideSEL);

- (void) override_setRightBarButtonItem:(UIBarButtonItem *)item animated:(BOOL)animated{   
    if (item && [item.target isKindOfClass:[QLPreviewController class]] && item.action == @selector(actionButtonTapped:)){
        QLPreviewController* qlpc = (QLPreviewController*)item.target;
        [self override_setRightBarButtonItem:qlpc.navigationItem.rightBarButtonItem animated: animated];
    }else{
        [self override_setRightBarButtonItem:item animated: animated];
    }
}

+ (void)load {
    MethodSwizzle(self, @selector(setRightBarButtonItem:animated:), @selector(override_setRightBarButtonItem:animated:));
}

void MethodSwizzle(Class c, SEL origSEL, SEL overrideSEL) {
    Method origMethod = class_getInstanceMethod(c, origSEL);
    Method overrideMethod = class_getInstanceMethod(c, overrideSEL);

    if (class_addMethod(c, origSEL, method_getImplementation(overrideMethod), method_getTypeEncoding(overrideMethod))) {
        class_replaceMethod(c, overrideSEL, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
    }else{
        method_exchangeImplementations(origMethod, overrideMethod);
    }
}

@end

Steve Jobs will hunt me in my dreams until I find a proper solution...