public BackgroundAppViewModel()
        {
            ClearFileCommand = new RelayCommand(() =>
            {
                fileController.ClearCacheAsync();
                Clear();
            }, () => { return(true); });

            Load();
            _isTaskRegistered = BackgroundDemoTask.IsTaskRegistered();
            attachTask();
            if (Windows.ApplicationModel.DesignMode.DesignModeEnabled)
            {
                return;
            }
            this.dispatcher = CoreWindow.GetForCurrentThread().Dispatcher;
        }
        private async void setRegisteredTask(bool register)
        {
            if (_isTaskRegistered != register)
            {
                if (_isTaskRegistered)
                {
                    dettachTask();
                    BackgroundDemoTask.UnregisterTask();
                    _isTaskRegistered = false;
                }
                else
                {
                    await BackgroundDemoTask.RegisterTaskAsync();

                    attachTask();
                    _isTaskRegistered = BackgroundDemoTask.IsTaskRegistered();
                    OnPropertyChanged("IsTaskRegistered");
                }
            }
        }