Team lead wants to exclude some files in documents storage class from backup.
My argument that those probably belong to NSCachesDirectory is in vain.
Moreover setting exclusion attribute like so

+ (BOOL)kit_addSkipBackupAttributeToURL:(NSURL *)url
{
    if (![[NSFileManager defaultManager] fileExistsAtPath:url.path]) {
        return NO;
    }
    NSError *error = nil;
    NSNumber *value = nil;
    BOOL success = [url getResourceValue:&value forKey:NSURLIsExcludedFromBackupKey error:&error];
    if (value.boolValue == YES) {
        NSLog(@"ALREADY Excluded %@ from backup", [url absoluteString]);
        return YES;
    }
    success = [url setResourceValue:[NSNumber numberWithBool:YES]
                             forKey:NSURLIsExcludedFromBackupKey
                              error:&error];
    if (!success){
        NSLog(@"Error excluding %@ from backup: %@", [url lastPathComponent], error);
    }
    success = [url getResourceValue:&value
                             forKey:NSURLIsExcludedFromBackupKey
                              error:&error];
    NSAssert(success, @"The backup exclusion attribute did not stick");
    NSLog(@"Excluded %@ from backup", [url absoluteString]);
    return success;
}

does not trip but listing the directory later on using ls -la@ {directoryname} does not show that attribute. Somehow it fell off.

They stick in Library/Cache though.

Thoughts on fitness of such a usage of backup exclusion attribute in documents domain?