title: Avoid navigation bar becoming visible when there's scrollable content beneath it
body: <p>I have a default navigation bar on iOS 15, initially the bar itself has a tranparent background.</p>
  <p><a href="https://i.stack.imgur.com/jGjo6.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jGjo6.png" alt="Default Navbar" /></a></p>
  <p>But when I scroll the view in the view controller, to make some content of it underneath the navigation bar. Then the bar suddenly has a visible background.</p>
  <p><a href="https://i.stack.imgur.com/9YwWt.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9YwWt.png" alt="With content underneath" /></a></p>
  <p>I haven't done any special setting to my navigation bar. And tried setting scrollEdgeAppearance with no luck.</p>
  <pre><code>if #available(iOS 13.0, *) {
    let barAppearance = UINavigationBarAppearance()
    barAppearance.configureWithTransparentBackground()
    navigationController?.navigationBar.scrollEdgeAppearance = barAppearance
  } 
  </code></pre>