UISearchBar increases navigation bar height in iOS 11

I have my UISearchBar being part of the navigation bar like:

 let searchBar = UISearchBar()
 //some more configuration to the search bar
 .....
 navigationItem.titleView = searchBar

After updating to iOS 11 something weird happened to the search bar in my app. On iOS 10 and prior I had my navigation bar looking like:

Now with iOS 11 I have:

As you can see there is difference in the rounding of the two search bars which does not bothers me. The problem is that the search bar increases the height of the navigation bar. So when I go to another controller it looks weird too:

In fact that weird black line's height plus the current navigation bar's height is equal to the height of navigation bar shown in the second picture ...

Any ideas how to get rid of the black line and having consistent navigation bar height across all view controllers ?

I got black line under NavigationBar with SearchBar in iOS 11 in two cases:

• when i pushed another ViewControllers from ViewController with UISearchBar

• when i dismissed ViewController with UISearchBar with "drag right to dismiss"

My solution was: adding this code to my ViewController with UISearchBar:

-(void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:animated];
    [self.navigationController.view setNeedsLayout]; // force update layout
    [self.navigationController.view layoutIfNeeded]; // to fix height of the navigation bar
}

Swift 4 Update

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    navigationController?.view.setNeedsLayout() // force update layout
    navigationController?.view.layoutIfNeeded() // to fix height of the navigation bar
}

You can add a constraint of height 44 to the search bar for iOS 11.

// Swift

if #available(iOS 11.0, *) {
    searchBar.heightAnchor.constraint(equalToConstant: 44).isActive = true
}

// Objective-C

if (@available(iOS 11.0, *)) {
    [searchBar.heightAnchor constraintEqualToConstant:44].active = YES;
}