问显示错误的xcode - ' appendingPathComponent‘不可用:改用URL上的appendingPathComponent

EN

 import Stripe

 class MyAPIClient: NSObject, STPCustomerEphemeralKeyProvider {
 let baseURL = "https://api.stripe.com"
 func createCustomerKey(withAPIVersion apiVersion: String, completion: @escaping STPJSONResponseCompletionBlock) {
 let url = self.baseURL.appendingPathComponent("ephemeral_keys")  /*1st error - 'appendingPathComponent' is unavailable: Use appendingPathComponent on URL instead.*/
 var urlComponents = URLComponents(url: url, resolvingAgainstBaseURL: false)! /*2nd error - Cannot convert value of type 'String' to expected argument type 'URL'*/
 urlComponents.queryItems = [URLQueryItem(name: "api_version", value: apiVersion)]
 var request = URLRequest(url: urlComponents.url!)
 request.httpMethod = "POST"
 let task = URLSession.shared.dataTask(with: request, completionHandler: { (data, response, error) in
 guard let response = response as? HTTPURLResponse,
 response.statusCode == 200,
 let data = data,
 let json = ((try? JSONSerialization.jsonObject(with: data, options: []) as? [String : Any]) as [String : Any]??) else {
            completion(nil, error)
            return
        }
        completion(json, nil)
    })
    task.resume()
   }
 }