Create Block-Based UIAlertViews Without the Hassle

UIAlertView+Blocks.h

//
//  UIAlertView+Blocks.h
//
//  Created by Patrick Perini on 3/22/12.
//  Copyright (c) 2012 Inspyre Technologies. MIT License.
//

#import <UIKit/UIKit.h>

@interface UIAlertView (Blocks) <UIAlertViewDelegate>

- (id)initWithTitle:(NSString *)title message:(NSString *)message cancelButtonTitle:(NSString *)cancelButtonTitle cancelButtonBlock:(void (^)())cancelBlock otherButtonTitlesAndBlocks:(id)otherButtonTitlesAndBlocks, ... NS_REQUIRES_NIL_TERMINATION;

@end

/*
 Example Use:
 
    void (^cancelBlock)() = ^()
    {
        NSLog(@"Canceled");
    };
    
    void (^okBlock)() = ^()
    {
        NSLog(@"OK!");
    };
    
    UIAlertView *myAlertView = [[UIAlertView alloc] initWithTitle: @"ALERT"
                                                          message: @"Gonna do some stuff, ok?"
                                                cancelButtonTitle: @"Cancel"
                                                cancelButtonBlock: cancelBlock
                                       otherButtonTitlesAndBlocks: @"OK", okBlock, nil];
    [myAlertView show];
 
 If the user presses the "Cancel" button, the word "Canceled" will log.
 Likewise, if the user presses the "OK" button, the word "OK!" will log.
 
 To add more buttons, alternate between button titles and their blocks for `otherButtonTitlesAndBlocks`.
 Think NSDictionary's objectsAndKeys...
*/

UIAlertView+Blocks.m

//
//  UIAlertView+Blocks.m
//
//  Created by Patrick Perini on 3/22/12.
//  Copyright (c) 2012 Inspyre Technologies. MIT License.
//

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

@implementation UIAlertView (Blocks)

static void *blocksKey;

- (id)initWithTitle:(NSString *)title message:(NSString *)message cancelButtonTitle:(NSString *)cancelButtonTitle cancelButtonBlock:(void (^)())cancelBlock otherButtonTitlesAndBlocks:(id)otherButtonTitlesAndBlocks, ...
{
    self = [self initWithTitle: title
                       message: message
                      delegate: self
             cancelButtonTitle: cancelButtonTitle
             otherButtonTitles: nil];
    if (self)
    {
        va_list args;
        va_start(args, otherButtonTitlesAndBlocks);
        
        NSMutableArray *buttonBlocks = [NSMutableArray array];
        [buttonBlocks addObject: cancelBlock];
        
        for (NSString *arg = otherButtonTitlesAndBlocks; arg != nil; arg = va_arg(args, NSString *))
        {
            [self addButtonWithTitle: arg];
            [buttonBlocks addObject: va_arg(args, void (^)())];
        }
        
        va_end(args);
        
        objc_setAssociatedObject(self,
                                 blocksKey,
                                 buttonBlocks,
                                 OBJC_ASSOCIATION_COPY_NONATOMIC);
    }
    return self;
}

- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
    NSMutableArray *buttonBlocks = objc_getAssociatedObject(self,
                                                            blocksKey);
    
    ((void (^)())[buttonBlocks objectAtIndex: buttonIndex])();
}

@end