How te retrieve the bundle identifier of a specific bundle

gistfile1.txt

    NSArray *files = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:[[NSBundle mainBundle] bundlePath] error:NULL];
    for (NSString *fileName in files)
    {
        NSString *path = [[NSBundle mainBundle] pathForResource:fileName ofType:nil];
        NSURL *url = [NSURL fileURLWithPath:path];
        // do something with `url`
        if ([fileName isEqualToString:@"MY_BUNDLE.bundle"])
        {
            NSLog(@"Found id : %@ for bundle : %@", [[NSBundle bundleWithURL:url] bundleIdentifier], fileName);
        }
    }