title: QLPreviewController nav bar blocks PDF content
body: <p>I'm working on a project that displays a PDF using <code>QLPreviewController</code> from two different views.  One view pushes the <code>QLPreviewController</code> onto the base navigation, and the other one is a modal view that brings the <code>QLPreviewController</code> up in modal.</p>
  
  <p>I had issues when I initially set this up with the push including setting the nav bar opacity and the nav bar blocking my PDF.  I was able to solve both issues by subclassing the <code>QLPreviewController</code>:</p>
  
  <pre><code>#import "CustomPreviewController.h"
  
  @interface CustomPreviewController ()
  
  @end
  
  @implementation CustomPreviewController
  
  -(id) init {
      self = [super init];
      if(self){
          // init
      } return self;
  }
  
  - (void) viewDidAppear:(BOOL)animated {
      [super viewDidAppear:animated];
      // set translucency of navigation bar
      self.navigationController.navigationBar.translucent = NO;
      // nav bar does not overlap content
      self.edgesForExtendedLayout = UIRectEdgeNone;
      self.automaticallyAdjustsScrollViewInsets = YES;
  }
  
  @end
  </code></pre>
  
  <p>However, now I need to view the same PDF from a different flow in the app.  For this design I need a modal pop up to a <code>UITableView</code>, then either a push or a modal from that tableview to a PDF in the <code>QLPreviewController</code>.  When I use the same push animation I get a delay and fracturing of the animation and a glitchy toolbar at the top. (<a href="https://stackoverflow.com/questions/25845135/quicklook-qlpreviewcontroller-some-problems-with-ios-8-but-everything-works-wit">See this post here</a>).  When I use a modal it animates smoothly but my <code>UINavigationBar</code> is hiding the top of the PDF and covering the page number.  Similar nav bar symptoms to the push issues in the linked post.  I have tried the solution proposed there, as well as attempting to hide the nav bar of the initial modal and the preview controller, to no avail.</p>
  
  <p>This might be an Apple bug/issue but if anyone has discovered a usable workaround any suggestions would be welcome.</p>