title: Xamarin binding default value in xaml
body: <p>I would to set my <code>IsVisible</code> property of an object in <code>Xaml</code> by default at <code>false</code>. But when I open the page, it is visible, then the binding variable is evaluated, and if it is <code>false</code>, becomes invisible.
  I want that it is not visible by default, and the if the binding variable is true, it should become visible.
  I've tried to insert a default value in my binding for <code>IsVisible</code> property of my object. I've tried <code>FallbackValue = Hidden</code> or <code>FallbackValue = Collapsed</code> and more, even for <code>TargetNullValue</code>, but it doesn't works. I obtain always a <code>XamlParseException</code>.</p>
  
  <p>Can anyone help me please?
  Thanks.</p>
  
  <p>Code (simplified):</p>
  
  <pre><code> &lt;Grid HorizontalOptions="FillAndExpand"
         IsVisible="{Binding Path=Info.IsVisible, Converter={StaticResource BooleanToStringConverter}, FallbackValue=Collapsed}"
  </code></pre>