BooleanToVisibilityConverterMarkupExtension

public class BooleanToVisibilityConverterMarkupExtension : MarkupExtension, IValueConverter
{
    private static BooleanToVisibilityConverterMarkupExtension converter;

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
       return converter ?? (converter = new BooleanToVisibilityConverterMarkupExtension());
    }

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var v = (bool?)value;
        return v.HasValue && v.Value ? Visibility.Visible : Visibility.Collapsed;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var v = (Visibility)value;
        return v == Visibility.Visible;
    }
}
 
<!-- usage in xaml -->
Visibility="{Binding IsVisible, Converter={converters:BooleanToVisibilityConverterMarkupExtension}}">>