public Friend GetFriendById(string id)
        {
            Friend friend = friendList.GetFriendById(id);

            if (friend != null)
            {
                return(friendList.GetFriendById(id).Copy());
            }
            return(null);
        }
        public async Task <PostList> GetPostToShowByUserId(string userId)
        {
            PostList   searchList = new PostList();
            FriendList friendList = await cloudUserSystem.GetFriendListByUserId(userId);

            foreach (var post in postList.Posts)
            {
                //user's post or friends' post which is not disable user
                if (friendList.GetFriendById(post.SenderId) != null && !post.IsDisable(userId) || post.SenderId == userId)
                {
                    searchList.AddPost(post);
                }
            }
            return(searchList);
        }