Runtime的使用1 【 objc_setAssociatedObject 类添加属性】

以view的点击事件UIGestureRecognizer为例子，使用block的方式进行回调。

首先我们创建一个UIGestureRecognizer的类别。

#import <UIKit/UIKit.h>typedef void(^MMGestureBlock)(id gestureRecognizer);@interface UIGestureRecognizer (Block)+ (instancetype)mm_gestureRecognizerWithActionBlock:(MMGestureBlock)block;@end

#import "UIGestureRecognizer+Block.h"#import <objc/runtime.h>@implementation UIGestureRecognizer (Block)static const int target_key;+ (instancetype)mm_gestureRecognizerWithActionBlock:(MMGestureBlock)block {    __typeof(self) weakSelf = self;    return [[weakSelf alloc]initWithActionBlock:block];}- (instancetype)initWithActionBlock:(MMGestureBlock)block {    self = [self init];    [self addActionBlock:block];    [self addTarget:self action:@selector(wk_tapClick:)];    return self;}- (void)addActionBlock:(MMGestureBlock)block {    if (block) {        objc_setAssociatedObject(self, &target_key, block, OBJC_ASSOCIATION_COPY_NONATOMIC);    }}- (void)wk_tapClick:(id)sender {        MMGestureBlock block = objc_getAssociatedObject(self, &target_key);    if (block) {        block(sender);    }}@end

我们使用objc_setAssociatedObject来给当前类添加一个关联。然后再使用objc_getAssociatedObject把关联的数据得到。然后进行后续的操作。

引入此类别#import"UIGestureRecognizer+Block.h"

UIView *viewM = [[UIView alloc]initWithFrame:CGRectMake(100, 100, 100, 100)];    viewM.backgroundColor = [UIColor grayColor];    [self.view addSubview:viewM];        [viewM addGestureRecognizer:[UITapGestureRecognizer mm_gestureRecognizerWithActionBlock:^(id gestureRecognizer) {        NSLog(@"viewM点击事件-------");    }]];

这样我们就可以使用此方法来更简单的使用点击事件了。