+ (NSURL *)dataStoreURLFromPackageURL:(NSURL *)URL {
NSString *storePath = [[URL relativePath] stringByAppendingPathComponent:[self fileStoreName]];
return [NSURL fileURLWithPath:storePath];
}

I accidently did not make storePath a pointer and the capitalization of ‘URL’ was off.

For dataStoreURLFromPackageURL:, use:
+ (NSURL *)dataStoreURLFromPackageURL:(NSURL *)URL {
NSString storePath = [[url relativePath] stringByAppendingPathComponent:[self fileStoreName]];
return [NSURL fileURLWithPath:storePath];
}

For packageURLFromDataStoreURL: it is much simpler, you can use:
+ (NSURL *)packageURLFromDataStoreURL:(NSURL *)URL {
NSString *storePath = [URL relativePath];
return [NSURL fileURLWithPath:[storePath stringByDeletingLastPathComponent]];
}

This removes the need for the NSDocumentSubcontroller subclass from having to check to see if a document exists, as the name translation is independent of an instantiated document. I do not know if some of the idioms are available from ruby, but in ObjC I use ’self’ in the class methods to make it polymorphic safe, i.e. subclasses can override the class method and have it still work. When the data store name is required in the instance methods I use [[self class] fileStoreName] for the same reason.

Your code helped me immensely! I had some problems porting it to Objective C (mainly a weird error that occurred if I didn’t pass an NSError to super’s writeToUrl:.. and the lack of RegExps) but I think it’s working now.

Besides the Recent Items thing, the window title icon seems to lock onto the data store, instead of the package (when opening a file). I don’t think that’s too hard to fix though.

Thank you!

I’ve done all the studied you mentioned in your article and, luckily, I found your article in google. I’ll try your suggestion in my application. Thanks a lot!!!