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

.m文件

#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

UIButton的扩展
.h文件

#import <UIKit/UIKit.h>

typedef void (^btnBlock)();

@interface UIButton (Block)

- (void)handelWithBlock:(btnBlock)block;

@end

.m文件

#import "UIButton+Block.h"
#import <objc/runtime.h>

static const char btnKey;

@implementation UIButton (Block)

- (void)handelWithBlock:(btnBlock)block
{
if (block)
{
objc_setAssociatedObject(self, &btnKey, block, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

[self addTarget:self action:@selector(btnAction) forControlEvents:UIControlEventTouchUpInside];
}

- (void)btnAction
{
btnBlock block = objc_getAssociatedObject(self, &btnKey);
block();
}

@end

tips: 使用objc_setAssociatedObject，需要引入头文件

#import <objc/runtime.h>

void objc_setAssociatedObject(id object, const void key, id value, objc_AssociationPolicy policy);id objc_getAssociatedObject(id object, const void
key);

这两个方法可以让一个对象和另一个对象关联，就是说一个对象可以保持对另一个对象的引用，并获取那个对象。有了这些，就能实现属性功能了。 policy可以设置为以下这些值：

enum {OBJC_ASSOCIATION_ASSIGN = 0,
OBJC_ASSOCIATION_RETAIN_NONATOMIC = 1,
OBJC_ASSOCIATION_COPY_NONATOMIC = 3,
OBJC_ASSOCIATION_RETAIN = 01
OBJC_ASSOCIATION_COPY = 01403
};

文／Lonely__（简书作者）

原文链接：http://www.jianshu.com/p/35df1ba1f107

著作权归作者所有，转载请联系作者获得授权，并标注“简书作者”。