UIAlertView with blocks support

UIAlertView+Blocks.h

//
//  UIAlertView+Blocks.h
//
//  Created by Matej Bukovinski on 19.7.11.
//  Copyright 2011 Guerrilla Code. All rights reserved.
//

#import <Foundation/Foundation.h>


@interface UIAlertView (Blocks) <UIAlertViewDelegate>

- (id)initWithTitle:(NSString *)title message:(NSString *)message;

#if NS_BLOCKS_AVAILABLE
- (void)addButtonWithTitle:(NSString *)title action:(dispatch_block_t)block;
- (void)addCancelButtonWithTitle:(NSString *)title action:(dispatch_block_t)block;
#endif

@end

UIAlertView+Blocks.m

//
//  UIAlertView+Blocks.m
//
//  Created by Matej Bukovinski on 19.7.11.
//  Copyright 2011 Guerrilla Code. All rights reserved.
//

#import "UIAlertView+Blocks.h"
#import <objc/runtime.h>


@implementation UIAlertView (Blocks)

#pragma mark - Accessors

- (NSMutableArray *)callbacks {
	static char kCallbacksKey;
	NSMutableArray *callbacks = (NSMutableArray *)objc_getAssociatedObject(self, &kCallbacksKey);
	if (!callbacks) {
		callbacks = [NSMutableArray array];
		objc_setAssociatedObject(self, &kCallbacksKey, callbacks, OBJC_ASSOCIATION_RETAIN);
	}
	return callbacks;
}

#pragma mark - Lifecycle

- (id)initWithTitle:(NSString *)title message:(NSString *)message {
	return [self initWithTitle:title message:message delegate:self cancelButtonTitle:nil otherButtonTitles:nil];
}

#if NS_BLOCKS_AVAILABLE

#pragma mark - Buttons

- (void)addButtonWithTitle:(NSString *)title action:(dispatch_block_t)block {
	[self addButtonWithTitle:title];
	if (!block) block = ^{};
	[[self callbacks] addObject:[block copy]];
}

- (void)addCancelButtonWithTitle:(NSString *)title action:(dispatch_block_t)block {
	[self setCancelButtonIndex:[self callbacks].count];
	[self addButtonWithTitle:title action:block];
}

#pragma mark - UIAlertViewDelegate

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
	dispatch_block_t callback = [[self callbacks] objectAtIndex:buttonIndex];
	if (callback) {
		callback();
	}
}

#endif

@end