Result expextation

sb.h

#import <UIKit/UIKit.h>

#define field(__TYPE__, __NAME__) __unsafe_unretained __TYPE__ __NAME__
#define group(__NAME__, __CODE__) struct __CODE__ __NAME__

struct RBGTagSelectionStoryboardIDs
{
    field(NSString*, name);
    group(controllers, {
        field(NSString*, tagList);
    });
    group(cells, {
        field(NSString*, tagListCell);
    });
};

#undef field
#undef group

@class RBGTagListCollectionViewController;

@interface RBGTagSelectionStoryboard : UIStoryboard

+ (instancetype)new;
+ (UIStoryboard *)storyboardWithName:(NSString *)name
                              bundle:(NSBundle *)storyboardBundleOrNil NS_UNAVAILABLE;

+ (struct RBGTagSelectionStoryboardIDs)IDs;
@property (nonatomic, readonly) struct RBGTagSelectionStoryboardIDs IDs;

- (RBGTagListCollectionViewController*)instantiateTagListViewController;

@end

@interface UIViewController (RBGTagSelectionStoryboard)

@property (nonatomic, readonly) RBGTagSelectionStoryboard* rbg_tagSelectionStoryboard;

@end

sb.m

#import "RBGTagSelectionStoryboard.h"

const struct RBGTagSelectionStoryboardIDs RBGTagSelectionStoryboardIDs = {
    .name = @"RBGTagSelectionStoryboard",
    .controllers = {
        .tagList = @"tag list collection view",
    },
    .cells = {
        .tagListCell = @"com.robe-guard.tag-list.cell",
    },
};

@implementation RBGTagSelectionStoryboard

+ (instancetype)new
{
    return (RBGTagSelectionStoryboard*)[super
                                        storyboardWithName:self.IDs.name
                                        bundle:[NSBundle bundleForClass:[self class]]];
}

+ (struct RBGTagSelectionStoryboardIDs)IDs
{
    return RBGTagSelectionStoryboardIDs;
}

- (struct RBGTagSelectionStoryboardIDs)IDs
{
    return [RBGTagSelectionStoryboard IDs];
}

- (RBGTagListCollectionViewController*)instantiateTagListViewController;
{
    return [self instantiateViewControllerWithIdentifier:self.IDs.controllers.tagList];
}

@end

@implementation UIViewController (RBGTagSelectionStoryboard)

- (RBGTagSelectionStoryboard *)rbg_tagSelectionStoryboard
{
    id sb = self.storyboard;
    if ([sb isKindOfClass:[RBGTagSelectionStoryboard class]]) {
        return sb;
    }
    
    return nil;
}

@end

Another implementations:
https://bitbucket.org/nut_code_monkey/ssgenerator
https://github.com/kluivers/storyboard-constants