Instance Variables for Objective C Categories

Question

I have a situation where it seems like I need to add instance variables to a category, but I know from Apple\'s docs that I can\'t do that. So I\'m wondering what the best a

Answer 1

It mentioned in many document's online that you can't create create new variable in category but I found a very simple way to achieve that. Here is the way that let declare new variable in category.

In Your .h file

@interface UIButton (Default)

   @property(nonatomic) UIColor *borderColor;

@end  

In your .m file

#import 
static char borderColorKey;

@implementation UIButton (Default)

- (UIColor *)borderColor
{
    return objc_getAssociatedObject(self, &borderColorKey);
}

- (void)setBorderColor:(UIColor *)borderColor
{
    objc_setAssociatedObject(self, &borderColorKey,
                             borderColor, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    self.layer.borderColor=borderColor.CGColor;
}

@end

That's it now you have the new variable.