title: Is there a way you could set the height of a CupertinoNavigationBar like you can with AppBar
body: <p>I have problem setting the size of my <code>CupertinoNavigationBar</code> manually, and I know you would be able to do it for the <code>appBar</code> using the <code>PreferredSize</code> Widget by doing the following:</p>
  
  <pre><code>appBar: PreferredSize(
    preferredSize: Size.fromHeight(60.0),
    child: AppBar(
      flexibleSpace: Widget(),
    )
  ),
  </code></pre>
  
  <p>However if you try this for the <code>CupertinoNavigationBar</code> you get an error that states: </p>
  
  <blockquote>
    <p>'AppBar' is not a subtype of type 'ObstructingPreferredSizeWidget'</p>
  </blockquote>
  
  <p>Is there any known way that you could set the height of the <code>CupertinoNavigationBar</code> manually?</p>