message: remove status bar constraint from navigation controller
diff: @interface ARTopMenuViewController ()
  @property (nonatomic, strong) UINavigationController *nav;
  -@property (nonatomic, strong) UIView *statusBarView;
  @property (nonatomic, strong) NSLayoutConstraint *statusBarVerticalConstraint;
  @end
  {
  [super viewDidLoad];
  - _statusBarView = [[UIView alloc] init];
  - _statusBarView.backgroundColor = UIColor.whiteColor;
  -
  - [self.view addSubview:_statusBarView];
  -
  - // Just a default value
  - _statusBarVerticalConstraint = [_statusBarView constrainHeight:@"20"];
  - [_statusBarView constrainWidthToView:self.view predicate:@"0"];
  - [_statusBarView alignTopEdgeWithView:self.view predicate:@"0"];
  - [_statusBarView alignLeadingEdgeWithView:self.view predicate:@"0"];
  -
  // Add the nav to our VC
  [self.nav willMoveToParentViewController:self];
  [self addChildViewController:self.nav];
  [self.nav didMoveToParentViewController:self];
  [self addChildViewController:self.nav];
  - [self.nav.view constrainTopSpaceToView:_statusBarView predicate:@"0"];
  + [self.nav.view alignTopEdgeWithView:self.view predicate:@"0"];
  [self.nav.view alignBottom:@"0" trailing:@"0" toView:self.view];
  [self.nav.view constrainWidthToView:self.view predicate:@"0"];
  }
  -- (CGFloat)statusBarHeight
  -{
  - // iPhone X support
  - if (@available(iOS 11.0, *)) {
  - return self.view.safeAreaInsets.top;
  - } else {
  - return 20;
  - }
  -}
  -
  -// safeAreaInsets for an iPhone X is null at viewDidLoad
  -// so we use viewDidLayoutSubviews to get the value eventually
  -
  -- (void)viewDidLayoutSubviews
  -{
  - [super viewDidLayoutSubviews];
  -
  - if (_statusBarVerticalConstraint.constant != [self statusBarHeight]) {
  - _statusBarVerticalConstraint.constant = [self statusBarHeight];
  - }
  -}
  @end
  