In ios11 searchBar's scopeButtons doesn't render correctly in tableHeaderView?

Question

iOS

Good day, I'm learning to make IOS applications. Unfortunately, I did not find a decent book on ios11 - I am studying at https://www.ozon.ru/context/detail/id/140304577/. before that I mastered 4 Swift. There are some inconsistencies with api occasionally, but usually the problem with finding an analogue is solved in a couple of minutes.
Faced a problem

@IBOutlet weak var tableView: UITableView!
    let sectionsTableIdentifier = "SectionsTableIdentifier"
    var names: [String: [String]]!
    var keys: [String]!
    var searchController: UISearchController!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        
        tableView.register(UITableViewCell.self, forCellReuseIdentifier: sectionsTableIdentifier)
        
        let path = Bundle.main.path(forResource: "sortednames", ofType: "plist")
        let nameDist = NSDictionary(contentsOfFile: path!)
        names = nameDist as! [String:[String]]
        keys = (nameDist!.allKeys as! [String]).sorted()
        
        
        let resultsController = SearchResultsController()
        resultsController.names = names
        resultsController.keys = keys
        searchController = UISearchController(searchResultsController: resultsController)

        let searchBar = searchController.searchBar
        
        searchBar.scopeButtonTitles = ["All", "Short", "Long"]
        searchBar.placeholder = "Enter a search term"
        
        searchBar.sizeToFit()
        tableView.tableHeaderView = searchBar
        
        searchController.searchResultsUpdater = resultsController
    }

Judging by the book in ios10, this should be displayed completely without any problems. But in the latest version, scopeButtons are not fully visible.