如何在iOS13中结合SearchController更改导航控制器的Backbutton-tintColor

let searchController = UISearchController(searchResultsController: nil)
navigationItem.searchController = searchController

if #available(iOS 13.0, *) {
    let appearance = UINavigationBarAppearance()
    appearance.configureWithDefaultBackground()
    appearance.buttonAppearance.normal.tintColor = UIColor.red // 设置Backbutton的颜色
    navigationItem.standardAppearance = appearance
    navigationItem.scrollEdgeAppearance = appearance
} else {
    // Fallback on earlier versions
    navigationController?.navigationBar.tintColor = UIColor.red // 设置Backbutton的颜色
}

searchController.obscuresBackgroundDuringPresentation = false