#Node Unarchive Delegate

Here's one for you: XCode's new SpriteKit scene editor doesn't allow you to change the class of nodes in the scene like interface builder. This is rather inconvenient if for example, you want to setup your custom sprite subclasses in the scene:

@interface MyHeroSprite : SKSpriteNode

- (void)jumpTo:(CGPoint)to;
- (void)levelUp:(MyHeroLevelEnum)level;

@end

@interface MyEnemySprite : SKSpriteNode

@property (nonatomic) BOOL isEvil;
- (void)die;

@end

...

This tricksy little class allows you to swap out nodes with your custom subclass by name during the unarchive process. I.e.

NADSubclassUnarchiveDelegate *delegate = [[NADSubclassUnarchiveDelegate alloc] init];
[delegate registerSubclassClass:[MyHeroSprite class] forNodeNamed:@"Hero"];
[delegate registerSubclassClass:[MyEnemySprite class] forNodeNames:@[ @"Alien1", @"Alien2", @"Alien3", ]];

NSString *nodePath = [[NSBundle mainBundle] pathForResource:file ofType:@"sks"];
NSData *data = [NSData dataWithContentsOfFile:nodePath options:NSDataReadingMappedIfSafe error:nil];
NSKeyedUnarchiver *arch = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
arch.delegate = delegate;
[arch setClass:[MyAwesomeScene class] forClassName:@"SKScene"];
MyAwesomeScene *scene = [arch decodeObjectForKey:NSKeyedArchiveRootObjectKey];
[arch finishDecoding];

...

###Is It Hack?

Nah. It seems valid enough given that I'm making valid use of the NSKeyedUnarchiverDelegate to replace decoded objects.

The only questionable architectural decision I've made is using instances NSKeyedArchiver and NSKeyedUnarchiver within the delegate to actually clone the node data into an instance of its subclass.