Objective-C Language Categories Adding a property with a category
Example
Properties can be added with categories using associated objects, a feature of the Objective-C runtime.
Note that the property declaration of retain, nonatomic matches the last argument to objc_setAssociatedObject. See Attach object to another existing object for explanations.
#import <objc/runtime.h>
@interface UIViewController (ScreenName)
@property (retain, nonatomic) NSString *screenName;
@end
@implementation UIViewController (ScreenName)
@dynamic screenName;
- (NSString *)screenName {
return objc_getAssociatedObject(self, @selector(screenName));
}
- (void)setScreenName:(NSString *)screenName {
objc_setAssociatedObject(self, @selector(screenName), screenName, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
@end
