Synthesize + objc_get/setAssociatedObject

CategoryProperty.h

#import <objc/runtime.h>
 
#define SYNTHESIZE(class, getter, setter) \
static const void *getter##PropertyKey = &getter##PropertyKey;\
- (type *)getter { \
    return objc_getAssociatedObject(self, getter##PropertyKey); \
} \
\
- (void)setter:(class *object) { \
    objc_setAssociatedObject(self, getter##PropertyKey, object, OBJC_ASSOCIATION_RETAIN);\
}