UIAlertView用block方式代替delegate

头文件

//
//  UIAlertView+Utils.h
//  UIView+Categories
//
//  Created by su xinde on 13-4-11.
//  Copyright (c) 2013年 su xinde. All rights reserved.
//

#import <UIKit/UIKit.h>

/*
 * Completion handler invoked when user taps a button.
 *
 * @param alertView The alert view being shown.
 * @param buttonIndex The index of the button tapped.
 */
typedef void(^UIAlertViewHandler)(UIAlertView *alertView, NSInteger buttonIndex);

/**
 * Category of `UIAlertView` that offers a completion handler to listen to interaction. This avoids the need of the implementation of the delegate pattern.
 *
 * @warning Completion handler: Invoked when user taps a button.
 *
 * typedef void(^UIAlertViewHandler)(UIAlertView *alertView, NSInteger buttonIndex);
 *
 * - *alertView* The alert view being shown.
 * - *buttonIndex* The index of the button tapped.
 */
@interface UIAlertView (Utils)

/**
 * Shows the receiver alert with the given handler.
 *
 * @param handler The handler that will be invoked in user interaction.
 */
- (void)showWithHandler:(UIAlertViewHandler)handler;

/**
 * Utility selector to show an alert with a title, a message and a button to dimiss.
 *
 * @param title The title of the alert.
 * @param message The message to show in the alert.
 * @param handler The handler that will be invoked in user interaction.
 */
+ (void)showWithTitle:(NSString *)title
              message:(NSString *)message
              handler:(UIAlertViewHandler)handler;

/**
 * Utility selector to show an alert with an "Error" title, a message and a button to dimiss.
 *
 * @param message The message to show in the alert.
 * @param handler The handler that will be invoked in user interaction.
 */
+ (void)showErrorWithMessage:(NSString *)message
                     handler:(UIAlertViewHandler)handler;

/**
 * Utility selector to show an alert with a "Warning" title, a message and a button to dimiss.
 *
 * @param message The message to show in the alert.
 * @param handler The handler that will be invoked in user interaction.
 */
+ (void)showWarningWithMessage:(NSString *)message
                       handler:(UIAlertViewHandler)handler;

/**
 * Utility selector to show a confirmation dialog with a title, a message and two buttons to accept or cancel.
 *
 * @param title The title of the alert.
 * @param message The message to show in the alert.
 * @param handler The handler that will be invoked in user interaction.
 */
+ (void)showConfirmationDialogWithTitle:(NSString *)title
                                message:(NSString *)message
                                handler:(UIAlertViewHandler)handler;

@end

实现文件

//
//  UIAlertView+Utils.m
//  UIView+Categories
//
//  Created by su xinde on 13-4-11.
//  Copyright (c) 2013年 su xinde. All rights reserved.
//

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

/*
 * Runtime association key.
 */
static NSString *kHandlerAssociatedKey = @"kHandlerAssociatedKey";

@implementation UIAlertView (Utils)

#pragma mark - Showing

/*
 * Shows the receiver alert with the given handler.
 */
- (void)showWithHandler:(UIAlertViewHandler)handler {
    
    objc_setAssociatedObject(self, (const void *)(kHandlerAssociatedKey), handler, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    
    [self setDelegate:self];
    [self show];
}

#pragma mark - UIAlertViewDelegate

/*
 * Sent to the delegate when the user clicks a button on an alert view.
 */
- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
    
    UIAlertViewHandler completionHandler = objc_getAssociatedObject(self, (const void *)(kHandlerAssociatedKey));
    
    if (completionHandler != nil) {
        
        completionHandler(alertView, buttonIndex);
    }
}

#pragma mark - Utility methods

/*
 * Utility selector to show an alert with a title, a message and a button to dimiss.
 */
+ (void)showWithTitle:(NSString *)title
              message:(NSString *)message
              handler:(UIAlertViewHandler)handler {
    
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title
                                                    message:message
                                                   delegate:nil
                                          cancelButtonTitle:@"OK"
                                          otherButtonTitles:nil];
    
    [alert showWithHandler:handler];
}

/*
 * Utility selector to show an alert with an "Error" title, a message and a button to dimiss.
 */
+ (void)showErrorWithMessage:(NSString *)message
                     handler:(UIAlertViewHandler)handler {
    
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error"
                                                    message:message
                                                   delegate:nil
                                          cancelButtonTitle:@"OK"
                                          otherButtonTitles:nil];
    
    [alert showWithHandler:handler];
}

/*
 * Utility selector to show an alert with a "Warning" title, a message and a button to dimiss.
 */
+ (void)showWarningWithMessage:(NSString *)message
                       handler:(UIAlertViewHandler)handler {
    
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Warning"
                                                    message:message
                                                   delegate:nil
                                          cancelButtonTitle:@"OK"
                                          otherButtonTitles:nil];
    
    [alert showWithHandler:handler];
}

/*
 * Utility selector to show a confirmation dialog with a title, a message and two buttons to accept or cancel.
 */
+ (void)showConfirmationDialogWithTitle:(NSString *)title
                                message:(NSString *)message
                                handler:(UIAlertViewHandler)handler {
    
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title
                                                    message:message
                                                   delegate:nil
                                          cancelButtonTitle:@"No"
                                          otherButtonTitles:@"Yes", nil];
    
    [alert showWithHandler:handler];
}

@end