UIImage+Caption.m

@interface UIImage (Caption)
 
@property (nonatomic, copy) NSString *caption;
 
@end

// Implementation

#import <objc/runtime.h> 
 
static const void *ImageCaptionKey = &ImageCaptionKey;
 
@implementation UIImage (Caption)
 
- (void)setCaption:(NSSting *)caption {
    objc_setAssociatedObject(self, ImageCaptionKey, caption, OBJC_ASSOCIATION_COPY_NONATOMIC);
}
 
- (NSString *)caption {
    return objc_getAssociatedObject(self, ImageCaptionKey);
}
 
@end