public void Refresh()
        {
            if (BoxDetailFile != null && BoxDetailFile.Count > 0)
            {
                BoxDetailFile.Clear();
            }
            if (BoxDetailFileChild != null && BoxDetailFileChild.Count > 0)
            {
                BoxDetailFileChild.Clear();
            }
            BoxClient _boxClient = ServiceManager.Instence().BoxClient;

            if (_boxClient != null)
            {
                InitBoxRootFolderItems(_boxClient);
            }
        }
        public async void InitBoxRootFolderItems(BoxClient client)
        {
            BoxCollection <BoxItem> items = null;

            if (BoxDetailFile == null)
            {
                BoxDetailFile = new ObservableCollection <FileEntity>();
            }
            if (BoxDetailFile != null && BoxDetailFile.Count > 0)
            {
                BoxDetailFile.Clear();
            }
            if (BoxDetailFileChild == null)
            {
                BoxDetailFileChild = new ObservableCollection <FileEntity>();
            }
            if (BoxDetailFileChild != null && BoxDetailFile.Count > 0)
            {
                BoxDetailFileChild.Clear();
            }
            try
            {
                if (client != null)
                {
                    items = await client.FoldersManager.GetFolderItemsAsync("0", 500);

                    if (items != null)
                    {
                        foreach (var item in items.Entries)
                        {
                            if (item != null)
                            {
                                var fileEntity = new FileEntity();
                                if (item.Type.ToLower().ToString().Equals("file"))
                                {
                                    var boxfile = await client.FilesManager.GetInformationAsync(item.Id);

                                    fileEntity.FileName = boxfile.Name;
                                    fileEntity.FileId   = boxfile.Id;
                                    fileEntity.FileSize = Convert.ToString(boxfile.Size);
                                    fileEntity.ParentID = boxfile.Parent.Id;
                                    fileEntity.IsFile   = true;
                                }
                                else if (item.Type.ToLower().ToString().Equals("folder"))
                                {
                                    var boxfolder = await client.FoldersManager.GetInformationAsync(item.Id);

                                    fileEntity.FileName = boxfolder.Name;
                                    fileEntity.FileId   = boxfolder.Id;
                                    fileEntity.FileSize = Convert.ToString(boxfolder.Size);
                                    fileEntity.ParentID = boxfolder.Parent.Id;
                                    fileEntity.IsFile   = false;
                                }
                                if (fileEntity != null)
                                {
                                    BoxDetailFile.Add(fileEntity);
                                }
                            }
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                throw;
            }
        }