Use background image on UISearchController iOS 11

I'm implementing an UISearchController to my UITableView but I'm struggling with the customization for iOS 11. My navigation bar is using a gradient image background that I want the search controller to match, but I haven't found a way to set the background image for UISearchController. It works perfectly on UISearchController as a TableHeaderView, but in iOS 11 barely any customization is passed on.

Current outcome:

Desired outcome:

This is the code I'm using: (called on viewDidLoad)

private func setupSearchController() {

    let searchController = UISearchController(searchResultsController: nil)

    // Convert CAGradientLayer to UIImage
    let gradient = Color.blue.gradient
    gradient.frame = searchController.searchBar.bounds
    UIGraphicsBeginImageContext(gradient.bounds.size)
    gradient.render(in: UIGraphicsGetCurrentContext()!)
    let gradientImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    // Setup the Search Controller
    searchController.searchBar.backgroundImage = gradientImage
    searchController.searchBar.isTranslucent = false
    searchController.searchResultsUpdater = self
    searchController.hidesNavigationBarDuringPresentation = false
    searchController.dimsBackgroundDuringPresentation = false
    searchController.obscuresBackgroundDuringPresentation = false
    searchController.searchBar.placeholder = "Search by transaction name"
    searchController.searchBar.tintColor = Color.custom(hexString: "FAFAFA", alpha: 1).value
    definesPresentationContext = true
    searchController.searchBar.delegate = self

    // Implement Search Controller
    if #available(iOS 11.0, *) {
        navigationItem.searchController = searchController
        navigationItem.hidesSearchBarWhenScrolling = false
        navigationController?.navigationBar.setBackgroundImage(gradientImage, for: .default)
    } else {
        tableView.tableHeaderView = searchController.searchBar
    }

}

Thanks to Krunal's answer I was able to find a decent solution after searching for quite some time.

This is how I came about implementing the background-image for iOS 11:

    // Implement Search Controller
    if #available(iOS 11.0, *) {
        if let navigationBar = self.navigationController?.navigationBar {
            navigationBar.barTintColor = UIColor(patternImage: gradientImage!)
        }
        if let textField = searchController.searchBar.value(forKey: "searchField") as? UITextField {
            if let backgroundview = textField.subviews.first {
                backgroundview.backgroundColor = UIColor.white
                backgroundview.layer.cornerRadius = 10;
                backgroundview.clipsToBounds = true;

            }
        }
        navigationItem.searchController = searchController
        navigationItem.hidesSearchBarWhenScrolling = false
    } else {
        tableView.tableHeaderView = searchController.searchBar
    }