绑定xamarin forms选择器值的正确方法

<Picker ItemsSource="{Binding Options}" />

this.BindingContext = new ViewModel();

public class ViewModel : INotifyPropertyChanged
{
    private string selectedOption;
    public string SelectedOption
    {
        get { return selectedOption; }
        set
        {
            if (selectedOption != value)
            {
                selectedOption = value;
                OnPropertyChanged(nameof(SelectedOption));
            }
        }
    }

    public List<string> Options { get; set; }

    // INotifyPropertyChanged implementation
    public event PropertyChangedEventHandler PropertyChanged;
    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

<Picker ItemsSource="{Binding Options}" SelectedItem="{Binding SelectedOption}" />