次のコードを使用して NSHTTPCookie を作成していますが、Cookie に httpOnly フラグを設定するオプションはありません
[cookieProperties setObject:@"name" forKey:NSHTTPCookieName];
[cookieProperties setObject:@"value" forKey:NSHTTPCookieValue];
[cookieProperties setObject:[NSNumber numberWithBool: NO] forKey:NSHTTPCookieDiscard];
[cookieProperties setObject:[dictionary objectForKey:@"isSecure"] forKey:NSHTTPCookieSecure];
[cookieProperties setObject:@"abc.xyz.com" forKey:NSHTTPCookieDomain];
[cookieProperties setObject:@"abc.xyz.com" forKey:NSHTTPCookieOriginURL];
[cookieProperties setObject:@"/" forKey:NSHTTPCookiePath];
[cookieProperties setObject:@"0" forKey:NSHTTPCookieVersion];