NSNotificationCenter+ObserverAdditions

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 *note))block;

- (void)unregisterObserversForObserver:(id)observer;

- (void)unregisterObserversForName:(NSString *)aName;

- (void)unregisterObserver:(id)observer name:(NSString *)aName;

@end

NSNotificationCenter+ObserverAdditions.m

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

static char notificationObserverKey;
static char notificationNameKey;

@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];
    
    // Data Structure to track observer,notification name information
    NSDictionary *observationRecord = [NSDictionary dictionaryWithObjectsAndKeys:observer,name,nil];
    [[self observationRecordListForObserver:registeredObserver] addObject:observationRecord];
	[[self observationRecordListForName:name] addObject:observationRecord];
}

- (void)unregisterObserversForObserver:(id)registeredObserver
{    
    [self removeObserversForObserver:registeredObserver forName:nil];
}

- (void)unregisterObserver:(id)obsrvr name:(NSString *)aName
{
    [self removeObserversForObserver:obsrvr forName:aName];
}

- (void)unregisterObserversForName:(NSString *)aName
{
	[self removeObserversForObserver:nil forName:aName];
}

#pragma mark- Internal Methods
// Hold array of Observers for Notification Observer
- (NSMutableArray *)observationRecordListForObserver:(id)obsrv
{
    NSMutableArray *observers = objc_getAssociatedObject(obsrv, &notificationObserverKey);
	if(!observers)
	{
		observers = [NSMutableArray array];
		objc_setAssociatedObject(obsrv, &notificationObserverKey, observers, OBJC_ASSOCIATION_RETAIN);
	}
    
	return observers;
}

// Hold an array of Observers for Notification Name
- (NSMutableArray *)observationRecordListForName:(NSString *)name
{
	NSMutableArray *observers = objc_getAssociatedObject(name, &notificationNameKey);
	if(!observers)
	{
		observers = [NSMutableArray array];
		objc_setAssociatedObject(name, &notificationNameKey, observers, OBJC_ASSOCIATION_RETAIN);
	}
    
	return observers;
}

- (void)removeObserversForObserver:(id)observr forName:(NSString *)name
{
   	if(observr)
	{
		NSMutableIndexSet *indexes = [NSMutableIndexSet indexSet];
		NSMutableArray *observersArr = nil;
		NSDictionary *observationRcrd = nil;

		observersArr = [self observationRecordListForObserver:observr];
		for(int index = 0; index < [observersArr count]; index++)
		{
			observationRcrd = [observersArr objectAtIndex:index];
			if(name)
			{
				if([observationRcrd objectForKey:name])
				{
					[self removeObserver:[observationRcrd objectForKey:name] 
									name:name 
								  object:nil];
					
					[indexes addIndex:index];
				}
			}
			else 
			{
				for(id observer in [observationRcrd allValues]) 
				{
					[self removeObserver:observer];
					[indexes addIndex:index];
				}
			}
		}
		[observersArr removeObjectsAtIndexes:indexes];
		observersArr = nil;
		observationRcrd = nil;
		indexes = nil;
	}
	else
	{
		NSMutableIndexSet *indexes = [NSMutableIndexSet indexSet];
		NSMutableArray *observersArr = nil;
		NSDictionary *observationRcrd = nil;

		observersArr = [self observationRecordListForObserverName:name];
		
		for(int index = 0; index < [observersArr count]; index++)
		{
			observationRcrd = [observersArr objectAtIndex:index];
			
			for(id observer in [observationRcrd allValues])
			{
				[self removeObserver:observer name:name object:nil];
				[indexes addIndex:index];
			}
		}
		[observersArr removeObjectsAtIndexes:indexes];
		indexes = nil;
		observersArr = nil;
		observationRcrd = nil;
	}
}

@end