public void RemoveContents(IEnumerable <int> ids, UserIdentity userIdentity)
        {
            var contentsToRemove = ContentBiz.Read(a => ids.Contains(a.Id) && a.AuthorId == userIdentity.UserId);
            HashSet <string> pictureNamesToRemove = new HashSet <string>();

            foreach (var content in contentsToRemove)
            {
                ContentBiz.Remove(content);
            }
            UnitOfWork.SaveChanges();
        }