objc_setAssociatedObject , objc_getAssociatedObject

#import <objc/runtime.h>

예제1)

// set

    {

        objc_setAssociatedObject(self, @"ShouldDismissModalViewLater", modalViewController, OBJC_ASSOCIATION_ASSIGN);

    }

    

    // get and using

    {

        UIViewController *modalVC = objc_getAssociatedObject(self, @"ShouldDismissModalViewLater");

        [modalVC dismissViewControllerAnimated:YES completion:nil];

    }

예제2)

// set

    {

        NSArray *gotArray;

        objc_setAssociatedObject(self, @"MyGotArray", gotArray, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

    }

    

    // get and using

    {

        NSArray *array = objc_getAssociatedObject(self, @"MyGotArray");

        [array enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {

            

        }];

    }

예제3)

Easier syntax

Alternatively you could use @selector(nameOfGetter) instead of creating a static pointer. Why? See http://stackoverflow.com/a/16020927/202451. Example:

- (NSArray *)laserUnicorns {
    return objc_getAssociatedObject(self, @selector(laserUnicorns));
}

- (void)setLaserUnicorns:(NSArray *)unicorns {
    objc_setAssociatedObject(self, @selector(laserUnicorns), unicorns, OBJC_ASSOCIATION_RETAIN_NONATOMIC); 
}