如何从ViewModel“重置”拾取器-- Xamarin iOS和MvvmCross

public class MyViewModel : INotifyPropertyChanged
{
    private ObservableCollection<string> _pickerItems;
    public ObservableCollection<string> PickerItems
    {
        get { return _pickerItems; }
        set
        {
            _pickerItems = value;
            OnPropertyChanged(nameof(PickerItems));
        }
    }

    private string _selectedItem;
    public string SelectedItem
    {
        get { return _selectedItem; }
        set
        {
            _selectedItem = value;
            OnPropertyChanged(nameof(SelectedItem));
        }
    }

    public MyViewModel()
    {
        // 初始化选择项列表
        PickerItems = new ObservableCollection<string>()
        {
            "Option 1",
            "Option 2",
            "Option 3"
        };

        // 设置默认选项
        SelectedItem = "Option 1";
    }

    public void ResetPicker()
    {
        // 重置选择项列表和当前选择
        PickerItems = new ObservableCollection<string>()
        {
            "Option 1",
            "Option 2",
            "Option 3",
            "Option 4" // 添加新的选项
        };
        SelectedItem = "Option 1"; // 重置为默认选项
    }

    // 实现INotifyPropertyChanged接口的代码...
}

var picker = new UIPickerView();
picker.Model = new PickerModel(viewModel.PickerItems.ToList());
picker.ShowSelectionIndicator = true;
picker.Frame = new CGRect(0, 0, 200, 200);
picker.SelectedRowInComponent(0);

viewModel.SetProperty(() => viewModel.SelectedItem, picker.Model.SelectedRowInComponent(0).ToString());