An Objective-C singleton class.

Singleton.h

//
//  Singleton.h
//

#import <Foundation/Foundation.h>

@interface Singleton : NSObject {

}

+ (id) instance;
+ (void) destroyInstance;
+ (void) destroyAllSingletons;

@end

Singleton.m

//
//  Singleton.m
//

#import "Singleton.h"

@implementation Singleton

static NSMutableDictionary* instances = nil;

+ (id) instance
{
	if (!instances) {
		instances = [[NSMutableDictionary alloc] init];
	}
	
	id instance = [instances objectForKey:self];
	if (!instance) {
		instance = [[[self alloc] init] autorelease];
		[instances setObject:instance forKey:self];
	}
	
	return instance;
}

+ (void) destroyInstance
{
	[instances removeObjectForKey:self];
}

+ (void) destroyAllSingletons
{
	[instances removeAllObjects];
}

@end