title: Unable to convert a string to Windows.UI.Xaml.Controls.IconElement
body: <p>I couldn't find how to use the <a href="http://msdn.microsoft.com/en-us/library/windows/apps/windows.ui.xaml.controls.symbolicon.symbol.aspx" rel="nofollow">SymbolIcon.Symbol</a> to change an appbar icon... </p>
  
  <p>This is to understand what I need to do:</p>
  
  <pre><code>if (SecondaryTile.Exists(ItemId))
  {
      PinToStart.Icon = "UnPin"; //instead of "Pin"
  }
  </code></pre>