private static string ContactToVcf(ContactModel contact)
        {
            VCard  vcard          = VCardUtils.ContactToVCard(contact);
            string seralizedVCard = VCardSerializer.Serialize(vcard);
            string filePath       = Path.Combine(HomePage.APP_DIR, String.Format("BC_{0}_{1}.vcf", contact.LastName, contact.Date.ToString("MM-dd-yyyy")));

            File.WriteAllText(filePath, seralizedVCard);

            return(filePath);
        }
        private static string ContactsToVcf(List <ContactModel> contacts)
        {
            IList <VCard> vcards  = VCardUtils.ContactsToVCards(contacts);
            StringBuilder builder = new StringBuilder();

            foreach (VCard vcard in vcards)
            {
                builder.Append(VCardSerializer.Serialize(vcard));
                builder.Append(Environment.NewLine);
            }

            string filePath = Path.Combine(HomePage.APP_DIR, String.Format("BC_{0}.vcf", DateTime.Now.ToString("MM-dd-yyyy HH.mm.ss")));

            File.WriteAllText(filePath, builder.ToString());

            return(filePath);
        }