为什么我的 UISearchBar 在点击时会缩小？

Question

When I load my code, the UISearchBar appears normally. However, after I tap the search field, the search bar shrinks and drops vertically lower. Code:

class MainViewController: UIViewController, UISearchBarDelegate {

    var searchBarController: UISearchController?
    var tableViewController: UITableViewController?
    var searchBar: UISearchBar?

    override func viewDidLoad() {
        super.viewDidLoad()

        self.view.backgroundColor = .blue

        let tableViewController = UITableViewController(style: .plain)
        let searchBarController = UISearchController(searchResultsController: tableViewController)

        self.searchBarController = searchBarController
        self.tableViewController = tableViewController

        self.searchBar = self.searchBarController?.searchBar
        self.searchBar?.frame = CGRect(x: 0, y: 50, width: self.view.frame.size.width, height: 75)
        self.searchBar?.searchBarStyle = .prominent
        self.view.addSubview(self.searchBar!)

    }    
}

Here is a visual before and after tapping:

Answer 1

UIkit will resize the searchcontroller's view on layoutSubviews() which will reset your frame.

If you want to control the size of the search bar independently, I'll suggest you make searchbar.translatesAutoresizingMaskIntoConstraints = false and/or in viewDidLayoutSubview() resize your searchbar with searchbar.frame = ...