iOS 给类别里面添加属性

#import <UIKit/UIKit.h>

@interface UIButton (Rayli)
@property (nonatomic,retain)NSString * str1;
@end

#import "UIButton+Rayli.h"
#import <objc/runtime.h>
static void * RayliStr;
@implementation UIButton (Rayli)
-(void)setStr1:(NSString *)str1
{
objc_setAssociatedObject(self, &RayliStr, str1, OBJC_ASSOCIATION_COPY);
}
-(NSString *)str1
{
return objc_getAssociatedObject(self, &RayliStr);
}
@end