objc 关联

• 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>

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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 = 01OBJC_ASSOCIATION_COPY = 01403};

• 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 = 01OBJC_ASSOCIATION_COPY = 01403};