private async Task TryGetSubFolders(bool withSecond) { if (_isLoading || _isLoaded) { return; } _isLoading = true; var subFolders = await CurrentFolder.GetFoldersAsync(); SubFolders.AddAll(subFolders.Select(it => new TreeViewItemModel(it, withSecond))); _isLoaded = true; _isLoading = false; }