message: Now uses system default styles for the navigation bar
diff: appearance.backButtonAppearance = [UIBarButtonItemAppearance new];
  appearance.backButtonAppearance.normal.titleTextAttributes = [self backAttributes];
  self.reactViewController.navigationItem.standardAppearance = appearance;
  - self.reactViewController.navigationItem.scrollEdgeAppearance = appearance;
  - self.reactViewController.navigationItem.compactAppearance = appearance;
  } else {
  bool transparent = self.barTintColor && CGColorGetAlpha(self.barTintColor.CGColor) == 0;
  [navigationBar setValue:@(transparent) forKey:@"hidesShadow"];
  