public void GetContacts(Action <IQueryable <ContactModel> > callback)
        {
            var timer = new DispatcherTimer();

            timer.Interval = TimeSpan.FromMilliseconds(1000);
            timer.Tick    += (o, e) =>
            {
                ((DispatcherTimer)o).Stop();
                callback(ContactDb.GetContacts());
            };
            timer.Start();
        }
 public void DeleteContact(ContactModel contact)
 {
     ContactDb.Delete(contact);
 }