Set default navigation bar and back button for app

Navigation bar appearance

// hide back button text
// fixes navigation title position
http://stackoverflow.com/questions/23853617/uinavigationbar-hide-back-button-text

- (void)setupNavigationBar
{
  [UINavigationBar appearance].barStyle = UIBarStyleDefault;
  [UINavigationBar appearance].barTintColor = [UIColor blueColor];
  [UINavigationBar appearance].translucent = NO;
  
  NSDictionary *attributes = @{NSForegroundColorAttributeName: [UIColor whiteColor],
                               NSFontAttributeName: [UIFont systemFontWithSize:17.0f]};
  [UINavigationBar appearance].titleTextAttributes = attributes;
}

- (void)setupBackButton
{
  UIImage *backArrow = [[UIImage imageNamed:@"back"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];
  [[UINavigationBar appearance] setBackIndicatorImage:backArrow];
  [[UINavigationBar appearance] setBackIndicatorTransitionMaskImage:backArrow];
  [[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0.0f, -60.0f) forBarMetrics:UIBarMetricsDefault];
}