Simplifying NSNotificationCenter block based observers

NSNotificationCenter+ObserverAdditions.h

#import <Foundation/Foundation.h>

@interface NSNotificationCenter (ObserverAdditions)

-(void) registerObserver: (id) observer
				 forName: (NSString *)name 
				  object:(id)obj
				   queue:(NSOperationQueue *)queue
			  usingBlock:(void (^)(NSNotification *))block;

-(void) unregisterObserversForObserver: (id) observer;

@end

NSNotificationCenter+ObserverAdditions.m

#import "NSNotificationCenter+ObserverAdditions.h"
#import <objc/runtime.h>

#define kNotificationObserversPaths		@"__notificationObservers"

@interface NSObject(InternalRegisterObserverMethods)
-(NSMutableArray *) notificationObserversForObserver: (id) observer;
@end

@implementation NSNotificationCenter (ObserverAdditions)

-(void) registerObserver: (id) registeredObserver
				 forName: (NSString *)name 
				  object: (id)obj
				   queue: (NSOperationQueue *)queue
			  usingBlock: (void (^)(NSNotification *note))block
{
	id observer = [self addObserverForName: name object: obj queue: queue usingBlock: block];
	[[self notificationObserversForObserver: registeredObserver] addObject: observer];
}

-(void) unregisterObserversForObserver: (id) registeredObserver;
{
	for( id observer in [self notificationObserversForObserver: registeredObserver] )
	{
		[self removeObserver: observer];
	}
}


#pragma mark- Internal Methods

-(NSMutableArray *) notificationObserversForObserver: (id) registeredObserver;
{
	NSMutableArray *observed = objc_getAssociatedObject( registeredObserver, kNotificationObserversPaths);
	if( !observed )
	{
		observed = [NSMutableArray array];
		objc_setAssociatedObject(  registeredObserver, kNotificationObserversPaths, observed, OBJC_ASSOCIATION_RETAIN);
	}
	return observed;
}

@end