Adding Properties to an Objective-C Category – Revisted
http://www.davidhamrick.com/2012/05/28/Adding-Properties-to-an-Objective-C-Category-Revisted.html
In my last post I wrote about adding properties to a category in objective-c. I have ended up using this feature quite a bit recently so I wrote a macro that will add the appropriate methods.
Before, when I wanted to add a category I would have to manually add the setter and getter.
static
char
kDHStyleKey
;
@interface
UIView
(DHStyleManager)
@property
(
nonatomic
,
copy
)
NSString
*
styleName
;
@end
@implementation
UIView
(DHStyleManager)
@dynamic
styleName
;
-
(
void
)
setStyleName:
(
NSString
*
)
styleName
{
objc_setAssociatedObject
(
self
,
&
kDHStyleKey
,
styleName
,
OBJC_ASSOCIATION_COPY
);
}
-
(
NSString
*
)
styleName
{
return
objc_getAssociatedObject
(
self
,
&
kDHStyleKey
);
}
@end
Now, all I need to do is use the macro to create the getters and setters.
@interface
UIView
(DHStyleManager)
@property
(
nonatomic
,
copy
)
NSString
*
styleName
;
@end
@implementation
UIView
(DHStyleManager)
ADD_DYNAMIC_PROPERTY
(
NSString
*
,
styleName
,
setStyleName
);
@end
All you need to do to use this macro is put this in a header file.
#define ADD_DYNAMIC_PROPERTY(PROPERTY_TYPE,PROPERTY_NAME,SETTER_NAME) \
@dynamic PROPERTY_NAME ; \
static char kProperty##PROPERTY_NAME; \
- ( PROPERTY_TYPE ) PROPERTY_NAME \
{ \
return ( PROPERTY_TYPE ) objc_getAssociatedObject(self, &(kProperty##PROPERTY_NAME ) ); \
} \
\
- (void) SETTER_NAME :( PROPERTY_TYPE ) PROPERTY_NAME \
{ \
objc_setAssociatedObject(self, &kProperty##PROPERTY_NAME , PROPERTY_NAME , OBJC_ASSOCIATION_RETAIN); \
} \