I think I found a stupid bug in NSURL when trying to read Mavericks Tags associated with the URL, along with other information for that URL resources.

README.txt

The output for the code below is as following, on my Mac. So, the first time that I ask to read the Tags it won't return localized filename or the UTI. But it will on a next invocation of the same code. Duh!


2013-10-24 00:10:26.780 Untitled 3[39076:507] Attributes WITHOUT Tags: {
    NSURLContentAccessDateKey = "2013-10-23 12:38:49 +0000";
    NSURLContentModificationDateKey = "2013-10-23 10:33:50 +0000";
    NSURLLocalizedNameKey = Applications;
    NSURLTypeIdentifierKey = "public.folder";
}
2013-10-24 00:10:26.781 Untitled 3[39076:507] Attributes WITH Tags: {
    NSURLContentAccessDateKey = "2013-10-23 12:38:49 +0000";
    NSURLContentModificationDateKey = "2013-10-23 10:33:50 +0000";
}
2013-10-24 00:10:26.781 Untitled 3[39076:507] Attributes WITH Tags AGAIN: {
    NSURLContentAccessDateKey = "2013-10-23 12:38:49 +0000";
    NSURLContentModificationDateKey = "2013-10-23 10:33:50 +0000";
    NSURLLocalizedNameKey = Applications;
    NSURLTypeIdentifierKey = "public.folder";
}

bug_with_tags.m

#import <Foundation/Foundation.h>

int main(int argc, char *argv[]) {
	NSAutoreleasePool *p = [[NSAutoreleasePool alloc] init];

	NSURL *url = [NSURL fileURLWithPath:@"/Applications"];
	
	NSDictionary *attrWithoutTags = [url resourceValuesForKeys:@[NSURLLocalizedNameKey, NSURLContentModificationDateKey, NSURLContentAccessDateKey, NSURLTypeIdentifierKey] error:NULL];
	
	NSDictionary *attrWithTags = [url resourceValuesForKeys:@[NSURLLocalizedNameKey, NSURLContentModificationDateKey, NSURLContentAccessDateKey, NSURLTypeIdentifierKey, NSURLTagNamesKey] error:NULL];
	
	NSDictionary *attrWithTagsAgain = [url resourceValuesForKeys:@[NSURLLocalizedNameKey, NSURLContentModificationDateKey, NSURLContentAccessDateKey, NSURLTypeIdentifierKey, NSURLTagNamesKey] error:NULL];
		
	NSLog(@"Attributes WITHOUT Tags: %@", attrWithoutTags);
	NSLog(@"Attributes WITH Tags: %@", attrWithTags);
	NSLog(@"Attributes WITH Tags AGAIN: %@", attrWithTagsAgain);


	[p release];
}