关联增加属性runtime.h

@interface NSObject (CategoryWithProperty)

@property (nonatomic, strong) NSObject *property;

@end

@implementation NSObject (CategoryWithProperty)

• (NSObject *)property {
  return objc_getAssociatedObject(self, @selector(property));
  }

• (void)setProperty:(NSObject *)value {
  objc_setAssociatedObject(self, @selector(property), value, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
  }