iOS copy files from main bundle to documents directory

I am trying to copy files that I add to a folder called "includes" to a folder on documents directory called also "includes".

I get a nil value for resContents. Why?

- (void)copyResources{

    NSString *sourcePath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"includes"];
    NSString *destPath = [[self applicationDocumentsDirectory] stringByAppendingPathComponent:@"includes"];

    NSArray* resContents = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:sourcePath error:NULL];

    for (NSString* obj in resContents){
        NSError* error;
        if (![[NSFileManager defaultManager] copyItemAtPath:[sourcePath stringByAppendingPathComponent:obj] toPath:[destPath stringByAppendingPathComponent:obj] error:&error]) {
            NSLog(@"Error: %@", error);;
        }
    }
}