public void ArchiveCompleted() { if (!File.Exists(User.Default.ArchiveFilePath)) { _window.File_Options(null, null); } if (!File.Exists(User.Default.ArchiveFilePath)) { return; } var archiveList = new TaskList(User.Default.ArchiveFilePath); var completed = _taskList.Tasks.Where(t => t.Completed); foreach (var task in completed) { archiveList.Add(task); _taskList.Delete(task); } UpdateDisplayedTasks(); }