UISearchBarSearchField 背景视图颜色

I am trying to change the background color of the search bar text field and i have searched and tried lots of solutions but those are not working.

所以，请任何人都可以告诉我确切的解决方案。我们如何更改搜索栏文本字段的背景颜色？

/// used to prepare searchController inside navigation.
private func prepareNavigationSearchControllerSetup() {
    self.title = AppConstant.kContacts
    let search = UISearchController(searchResultsController: nil)
    search.searchResultsUpdater = self
    search.searchBar.cornerRadius = 10.0
    search.searchBar.textField?.backgroundColor = .red
    search.searchBar.textField?.tintColor = .yellow
    self.navigationItem.searchController = search
    self.navigationItem.hidesSearchBarWhenScrolling = false
}

extension UISearchBar {

    var textField: UITextField? {
        let subViews = subviews.flatMap { $0.subviews }
        return (subViews.filter { $0 is UITextField }).first as? UITextField
    }
}

经过更多搜索后，我找到了对我有用的正确答案。

if #available(iOS 11.0, *) {
        if let textfield = search.searchBar.value(forKey: "searchField") as? UITextField {
            textfield.textColor = UIColor.blue

            if let backgroundview = textfield.subviews.first {
                backgroundview.backgroundColor = UIColor.white
                backgroundview.layer.cornerRadius = 10;
                backgroundview.clipsToBounds = true;
            }
        }

  }