title: Show a value in case of NULL in MVVMCross
body: <p>I have the following <code>NullableConverter</code> class. However when I run my application, it does not show anything in the <code>TextView</code>, how I could able to show 0 if the value is null? Is it possible to do it in the <code>axml</code>?</p>
  
  <pre><code>public class NullableValueConverter : MvxValueConverter
  {
      public override object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
      {
          return value;
      }
  
      public override object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
      {
          if (value == null || string.IsNullOrEmpty(value.ToString()))
          {
              return null;
          }
  
          return value;
      }
  }
  </code></pre>
  
  <p>and inside my view:</p>
  
  <pre><code>local:MvxBind="Text Age,Converter=Nullable;"
  </code></pre>