objc_getAssociatedObject & objc_setAssociatedObject example

associatedObjExample.m

       static char overviewKey;
        
        
        NSArray *array =
        
        [[NSArray alloc] initWithObjects:@"One", @"Two", @"Three", nil];
        
        // For the purposes of illustration, use initWithFormat: to ensure
        
        // the string can be deallocated
        
        NSString *overview =
        
        [[NSString alloc] initWithFormat:@"%@", @"First three numbers"];
        
        
        
        objc_setAssociatedObject (
                                  
                                  array,
                                  
                                  &overviewKey,
                                  
                                  overview,
                                  
                                  OBJC_ASSOCIATION_RETAIN
                                  
                                  );

        
        
        NSString *payload = objc_getAssociatedObject(array, &overviewKey);

        NSLog(@"%@",payload);