title: 'splitViewController:willHideViewController:withBarButtonItem:forPopoverController:' is deprecated: first deprecated in iOS 8.0
body: <p>I'm currently updating some old apps and I'm getting this warning.
  Sorry in advance if it's an obvious fix. I can't find exactly what to do online.</p>
  
  <p>Warning:</p>
  
  <blockquote>
    <p>'splitViewController:willHideViewController:withBarButtonItem:forPopoverController:' is deprecated: first deprecated in iOS 8.0 - Use splitViewController:willChangeToDisplayMode: and displayModeButtonItem instead</p>
  </blockquote>
  
  <p>My code section is:</p>
  
  <pre><code>if (!isLandscape) {
      [self splitViewController:splitViewController willHideViewController:master withBarButtonItem:button forPopoverController:popover];
  }
  else if (isLandscape) {
      [self splitViewController:splitViewController willShowViewController:master invalidatingBarButtonItem:button];
  }
  </code></pre>