这个问题通常是由于没有将委托方法设置为 ViewController 的委托所导致的。在 ViewController 中实现登录委托方法：

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let appleIDProvider = ASAuthorizationAppleIDProvider()
        let request = appleIDProvider.createRequest()
        request.requestedScopes = [.fullName, .email]

        let authController = ASAuthorizationController(authorizationRequests: [request])
        authController.presentationContextProvider = self
        authController.delegate = self
        authController.performRequests()
    }
}

extension ViewController: ASAuthorizationControllerDelegate {

    func authorizationController(controller: ASAuthorizationController, didCompleteWithAuthorization authorization: ASAuthorization) {
        // 委托被调用，处理登录返回结果
    }

    func authorizationController(controller: ASAuthorizationController, didCompleteWithError error: Error) {
        // 委托被调用，处理登录错误
    }
}

extension ViewController: ASAuthorizationControllerPresentationContextProviding {

    func presentationAnchor(for controller: ASAuthorizationController) -> ASPresentationAnchor {
        return self.view.window!
    }
}

然后在您的登录按钮的操作中将 ViewController 实例设置为授权控制器的委托：

// 在您的登录按钮操作中设置委托
let authController = ASAuthorizationController(authorizationRequests: [request])
authController.presentationContextProvider = self
authController.delegate = self
authController.performRequests()

后续在登录成功或失败时，您实现的委托方法 authorizationController(controller:didCompleteWithAuthorization:) 和 authorizationController(controller:didCompleteWithError:) 将会被调用。