Simple Objective-C take on Robert Penner's Signals-AS3

Signal.h

//
//  Signal.h
//
//  Created by Eric-Paul Lecluse on 22-01-11.
//  Copyright 2011 epologee. All rights reserved.
//
//	This class was actually inspired and named by the brilliant work of Robert Penner & friends
//  with the ActionScript 3.0 library called Signals: https://github.com/robertpenner/as3-signals
//	It's not even close to a port, but it meets the demands of my current project.

#import <Foundation/Foundation.h>

@interface Signal : NSObject

-(void)add:(id)listener withSelector:(SEL)selector;
-(void)add:(id)listener withSelector:(SEL)selector oneShot:(BOOL)oneShot;
-(void)addTrigger:(Signal *)listener;
-(void)addTrigger:(Signal *)listener oneShot:(BOOL)oneShot;

-(void)removeAllListeners;

-(void)dispatch;
-(void)dispatchWithUserInfo:(NSDictionary *)userInfo;

@end

Signal.m

//
//  Signal.m
//
//  Created by Eric-Paul Lecluse on 22-01-11.
//  Copyright 2011 epologee. All rights reserved.
//

#import "Signal.h"

@interface Signal ()
@property (nonatomic, retain) NSMutableSet *listeners;
@end

@implementation Signal

@synthesize listeners;

-(id) init {
	self = [super init];
	
	if (self) {
		self.listeners = [[[NSMutableSet alloc] init] autorelease];
	}
	
	return self;
}

-(void) dealloc {
	self.listeners = nil;
	
	[super dealloc];
}

-(void)add:(id)listener withSelector:(SEL)selector {
	[self add:listener withSelector:selector oneShot:NO];
}

-(void)add:(id)listener withSelector:(SEL)selector oneShot:(BOOL)oneShot {
	NSArray *objects = [NSArray arrayWithObjects:listener, [NSValue valueWithPointer:selector], [NSNumber numberWithBool:oneShot], nil];
	NSArray *keys = [NSArray arrayWithObjects:@"listener", @"selector", @"oneShot", nil];
	[self.listeners addObject:[NSDictionary	dictionaryWithObjects:objects forKeys:keys]];
}

-(void)addTrigger:(Signal *)listener {
	[self addTrigger:listener oneShot:NO];
}

-(void)addTrigger:(Signal *)listener oneShot:(BOOL)oneShot {
	NSArray *objects = [NSArray arrayWithObjects:listener, [NSNumber numberWithBool:oneShot], nil];
	NSArray *keys = [NSArray arrayWithObjects:@"listener", @"oneShot", nil];
	[self.listeners addObject:[NSDictionary	dictionaryWithObjects:objects forKeys:keys]];
}

-(void)removeAllListeners {
	[self.listeners removeAllObjects];
}

-(void)dispatch {
	[self dispatchWithUserInfo:nil];
}

-(void)dispatchWithUserInfo:(NSDictionary *)userInfo {
	NSMutableSet *remove = [[[NSMutableSet alloc] init] autorelease];
	
	for (NSDictionary *listenerOptions in self.listeners) {
		id listener = [listenerOptions objectForKey:@"listener"];
		BOOL oneShot = [[listenerOptions objectForKey:@"oneShot"] boolValue];
		
		if ([listener isKindOfClass:[Signal class]]) {
			[listener dispatchWithUserInfo:userInfo];
		} else {
			SEL selector = [[listenerOptions objectForKey:@"selector"] pointerValue];
			
			if ([listener respondsToSelector:selector]) {
				NSMethodSignature *msig = [listener methodSignatureForSelector:selector];
				if (msig != nil) {
					NSUInteger nargs = [msig numberOfArguments];
					if (nargs == 2) {
						// The first two arguments are self and SEL
						[listener performSelector:selector];
					} else if (nargs == 3) {
						// The third argument is actually the first parameter of the method.
						// For now, this only works with userInfo NSDictionary objects.
						[listener performSelector:selector withObject:userInfo];
					} else {
						// well yes, what else?
					}
				}
				
			}	
		}
		
		if (oneShot) {
			[remove addObject:listenerOptions];
		}			
	}
	
	[self.listeners minusSet:remove];
}


@end