objc_setAssociatedObject与Block的简单使用

• UIAlertView的扩展

.h文件

#import <UIKit/UIKit.h>typedef void (^successBlock)(NSInteger buttonIndex);@interface UIAlertView (Block)<UIAlertViewDelegate>- (void)showWithBlock:(successBlock)block;@end

#import "UIAlertView+Block.h"

#import <objc/runtime.h>static const char alertKey;@implementation UIAlertView (Block)- (void)showWithBlock:(successBlock)block{    if (block)    {        objc_setAssociatedObject(self, &alertKey, block, OBJC_ASSOCIATION_RETAIN_NONATOMIC);        self.delegate = self;    }    [self show];}- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{    successBlock block = objc_getAssociatedObject(self, &alertKey);    block(buttonIndex);}@end

tips: 使用objc_setAssociatedObject，需要引入头文件 #import <objc/runtime.h>