ios15NavigationBar.swift

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        
        if #available(iOS 15.0, *){
            let appearance = UINavigationBarAppearance()
            appearance.configureWithOpaqueBackground()
            appearance.backgroundColor = UIColor(red: 0.0/255.0, green: 125/255.0, blue: 0.0/255.0, alpha: 1.0)
            appearance.titleTextAttributes = [.foregroundColor: UIColor.white]
            UINavigationBar.appearance().tintColor = .white
            UINavigationBar.appearance().standardAppearance = appearance
            UINavigationBar.appearance().scrollEdgeAppearance = UINavigationBar.appearance().standardAppearance
        }else{
            UINavigationBar.appearance().barTintColor = UIColor(red: 0.0/255.0, green: 125/255.0, blue: 0.0/255.0, alpha: 1.0)
            UINavigationBar.appearance().titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white]
            UINavigationBar.appearance().tintColor = .white
        }
        
        //...
        return true
    }
}