Toggling Windows Phone App Bar Visibility
March 27, 2014Quick note on changing the visibility of an app bar in a Windows Phone app.
Toggling the visibility of a page’s app bar from code-behind is slightly different than most other controls. Unlike other UI elements, the visibility of the app bar on a page should note be set using the app bar’s name – this could result in null reference exceptions when the app bar’s visibility is set to false. Instead (and actually a bit more straightforward) the app bar’s visibility should be set using the page’s ApplicationBar
property: