title: Bug when swiping from view with uinavigationbar to one without
body: <p>I have an application with 2 viewcontrollers, ViewController and NextViewController. ViewController does not have a navigation bar and has a white status bar. NextViewController does have a navigation bar and has a black (default) status bar. I have encountered a bug when swiping back to ViewController from NextViewController and cancelling the swipe where the navigation bar on NextViewController will disappear. The storyboard simply has the two views with a button and an action segue. The bug does not always happen, but often enough to be a problem. The bug has to do with the method <code>- (UIStatusBarStyle) preferredStatusBarStyle</code>, as everything works fine when I remove the methods.</p>
  
  <p>Can I somehow stop this bug from happening while still having a white status bar on my ViewController and having the swipe enabled or am I forced to remove either functionality?</p>
  
  <p>ViewController</p>
  
  <pre><code>@implementation ViewController
  
  - (void)viewDidLoad {
      [super viewDidLoad];
      [self setNeedsStatusBarAppearanceUpdate];
  }
  
  - (void) viewWillAppear:(BOOL)animated {
      [super viewWillAppear:animated];
      [self.navigationController setNavigationBarHidden:YES animated:YES];
  }
  
  - (UIStatusBarStyle) preferredStatusBarStyle {
      return UIStatusBarStyleLightContent;
  }
  </code></pre>
  
  <p>NextViewController</p>
  
  <pre><code>@implementation NextViewController
  
  - (void)viewDidLoad {
      [super viewDidLoad];
      [self setNeedsStatusBarAppearanceUpdate];
  }
  
  - (void) viewWillAppear:(BOOL)animated {
      [super viewWillAppear:animated];
      [self.navigationController setNavigationBarHidden:NO animated:YES];
  }
  
  -(UIStatusBarStyle)preferredStatusBarStyle{
      return UIStatusBarStyleDefault;
  }
  </code></pre>
  
  <p>Other possibly relevant info: Experiencing the issue on an iPhone 5s with iOS 8, but it also happens on the simulator with iOS 9. View controller-based status bar appearance is set to the default, YES. </p>