Catogory如何添加属性

typedef struct category_t {
    const char *name;  //类的名字
    classref_t cls;  //类
    struct method_list_t *instanceMethods;  //category中所有给类添加的实例方法的列表
    struct method_list_t *classMethods;  //category中所有添加的类方法的列表
    struct protocol_list_t *protocols;  //category实现的所有协议的列表
    struct property_list_t *instanceProperties;  //category中添加的所有属性
} category_t;

#import <UIKit/UIKit.h>

@interface UIViewController (Router)

/** 参数字典 */
@property (nonatomic, strong) NSDictionary *paramDic;

@end

#import "UIViewController+Router.h"
#import <objc/runtime.h>

static const void *ParamDicKey = &ParamDicKey;

@implementation UIViewController (Router)

- (void)setParamDic:(NSDictionary *)paramDic
{
    objc_setAssociatedObject(self, ParamDicKey, paramDic, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (NSDictionary *)paramDic
{
    return objc_getAssociatedObject(self, ParamDicKey);
}

@end