/// <summary>
        /// 修改待办事项
        /// </summary>
        /// <returns></returns>
        private async Task ModifyToDo()
        {
            IsLoading = Visibility.Visible;

            //离线模式
            if (App.isInOfflineMode)
            {
                //修改当前列表
                MyToDos.ToList().Find(sche =>
                {
                    if (sche.ID == NewToDo.ID)
                    {
                        return(true);
                    }
                    else
                    {
                        return(false);
                    }
                }).Content = NewToDo.Content;

                await SerializerHelper.SerializerToJson <ObservableCollection <ToDo> >(MyToDos, SerializerFileNames.ToDoFileName, true);

                Messenger.Default.Send(new GenericMessage <string>(""), MessengerTokens.RemoveScheduleUI);

                NewToDo = new ToDo();

                Messenger.Default.Send(new GenericMessage <ObservableCollection <ToDo> >(MyToDos), MessengerTokens.UpdateTile);

                return;
            }
            //非离线模式
            else
            {
                var resultUpdate = await PostHelper.UpdateContent(NewToDo.ID, NewToDo.Content, NewToDo.Category);

                if (resultUpdate)
                {
                    MyToDos.ToList().Find(sche =>
                    {
                        if (sche.ID == NewToDo.ID)
                        {
                            return(true);
                        }
                        else
                        {
                            return(false);
                        }
                    }).Content = NewToDo.Content;

                    Messenger.Default.Send(new GenericMessage <string>(""), MessengerTokens.RemoveScheduleUI);
                    NewToDo = new ToDo();

                    Messenger.Default.Send(new GenericMessage <ObservableCollection <ToDo> >(MyToDos), MessengerTokens.UpdateTile);
                }
            }
            IsLoading = Visibility.Collapsed;
        }
        /// <summary>
        /// 完成待办事项
        /// </summary>
        /// <param name="id">待办事项的ID</param>
        /// <returns></returns>
        private async Task CompleteTodo(string id)
        {
            try
            {
                var currentMemo = MyToDos.ElementAt(MyToDos.ToList().FindIndex(sch =>
                {
                    if (sch.ID == id)
                    {
                        return(true);
                    }
                    else
                    {
                        return(false);
                    }
                }));
                currentMemo.IsDone = !currentMemo.IsDone;

                await SerializerHelper.SerializerToJson <ObservableCollection <ToDo> >(MyToDos, "myschedules.sch", true);

                if (!App.isInOfflineMode)
                {
                    var isDone = await PostHelper.FinishSchedule(id, currentMemo.IsDone? "1" : "0");

                    if (isDone)
                    {
                        await PostHelper.SetMyOrder(LocalSettingHelper.GetValue("sid"), ToDo.GetCurrentOrderString(MyToDos));

                        Messenger.Default.Send(new GenericMessage <ObservableCollection <ToDo> >(MyToDos), MessengerTokens.UpdateTile);
                    }
                }
                else
                {
                    Messenger.Default.Send(new GenericMessage <ObservableCollection <ToDo> >(MyToDos), MessengerTokens.UpdateTile);
                }
            }
            catch (Exception e)
            {
                var task = ExceptionHelper.WriteRecord(e);
            }
        }
        /// <summary>
        /// 删除todo
        /// </summary>
        /// <param name="id">ID</param>
        /// <returns></returns>
        /// 先从列表删除,然后把列表内容都序列化保存,接着:
        /// 1.如果已经登陆的,尝试发送请求;
        /// 2.离线模式,不用管
        private async Task DeleteToDo(string id)
        {
            try
            {
                var itemToDeleted = MyToDos.ToList().Find(s =>
                {
                    if (s.ID == id)
                    {
                        return(true);
                    }
                    else
                    {
                        return(false);
                    }
                });

                DeletedToDos.Add(itemToDeleted);
                await SerializerHelper.SerializerToJson <ObservableCollection <ToDo> >(DeletedToDos, SerializerFileNames.DeletedFileName, true);

                MyToDos.Remove(itemToDeleted);
                UpdateDisplayList(SelectedCate);
                await SerializerHelper.SerializerToJson <ObservableCollection <ToDo> >(MyToDos, SerializerFileNames.ToDoFileName, true);


                if (!App.isInOfflineMode)
                {
                    var result = await PostHelper.DeleteSchedule(id);

                    await PostHelper.SetMyOrder(LocalSettingHelper.GetValue("sid"), ToDo.GetCurrentOrderString(MyToDos));
                }

                Messenger.Default.Send(new GenericMessage <ObservableCollection <ToDo> >(MyToDos), MessengerTokens.UpdateTile);
            }
            catch (Exception e)
            {
                var task = ExceptionHelper.WriteRecord(e);
            }
        }
        /// <summary>
        /// 改变类别
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        private async Task ChangeCategory(string id)
        {
            var scheduleToChange = MyToDos.ToList().Find(s =>
            {
                if (s.ID == id)
                {
                    return(true);
                }
                else
                {
                    return(false);
                }
            });

            if (scheduleToChange != null)
            {
                scheduleToChange.Category++;
                if (!App.IsNoNetwork && !App.isInOfflineMode)
                {
                    await PostHelper.UpdateContent(id, scheduleToChange.Content, scheduleToChange.Category);
                }
            }
        }