private void ApplicationBarIconButton_Save_Click(object sender, EventArgs e)
        {
            // TODO: Add save operation.
            SettingsRepository settingsRepository = new SettingsRepository();

            Settings settings = settingsRepository.Get();

            // TODO: Add robustness here, probably mostly in input validation.
            ListPickerItem expireItem = this.ExpireAfterDays.SelectedItem as ListPickerItem;

            if (expireItem != null)
            {
                settings.ExpireAfterDays = int.Parse(expireItem.Tag.ToString());
            }

            ListPickerItem item = this.UnitType.SelectedItem as ListPickerItem;

            if (item != null)
            {
                settings.UnitType =
                    (UnitType)Enum.Parse(
                        typeof(UnitType),
                        item.Content.ToString(),
                        false);
            }

            settingsRepository.Save(settings);

            App.ViewModel.LoadData();

            NavigationService.GoBack();
        }