UISearchBar increases navigation bar height in iOS 11

I believe in iOS 11 UISearchBar now has the height equals to 56, and UINavigationBar uses autolayout to fit its subviews hence it increases the height. If you still want to have UISearchBar as titleView as in pre-iOS 11, I found out the best way to do it is to embed UISearchBar in a custom view, and set this view's height to 44, and assign it to navigationItem.titleView

class SearchBarContainerView: UIView {  

    let searchBar: UISearchBar  

    init(customSearchBar: UISearchBar) {  
        searchBar = customSearchBar  
        super.init(frame: CGRect.zero)  

        addSubview(searchBar)  
    }

    override convenience init(frame: CGRect) {  
        self.init(customSearchBar: UISearchBar())  
        self.frame = frame  
    }  

    required init?(coder aDecoder: NSCoder) {  
        fatalError("init(coder:) has not been implemented")  
    }  

    override func layoutSubviews() {  
        super.layoutSubviews()  
        searchBar.frame = bounds  
    }  
}  

class MyViewController: UIViewController {  

    func setupNavigationBar() {  
        let searchBar = UISearchBar()  
        let searchBarContainer = SearchBarContainerView(customSearchBar: searchBar)  
        searchBarContainer.frame = CGRect(x: 0, y: 0, width: view.frame.width, height: 44)  
        navigationItem.titleView = searchBarContainer  
    }  
} 

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
}

try this code on "ACKNOWLEDGEMENTS" view controller in viewDidLoad

self.extendedLayoutIncludesOpaqueBars = true

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;
}