private async void SaveMeetingAsync()
        {
            if (Meeting.IsAllDay)
            {
                EnsureAllDay();
            }

            Meeting newMeeting;

            using (new Loading(this))
            {
                newMeeting = await(string.IsNullOrEmpty(Meeting.Id) ?
                                   GraphService.CreateEvent(Meeting) :
                                   GraphService.UpdateEvent(Meeting));
            }

            if (newMeeting != null)
            {
                foreach (var att in _attachments.Where(x => string.IsNullOrEmpty(x.Id)))
                {
                    using (new Loading(this))
                    {
                        await GraphService.AddEventAttachment(newMeeting.Id, att);
                    }
                }

                UI.Publish(newMeeting);
                GoBack();
            }
        }