Face IDでログイン！Sign in with AppleをiOSアプリに組み込む

import UIKit
// 1. インポート
import AuthenticationServices

class ViewController: UIViewController {

    @IBOutlet weak var stackView: UIStackView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        setupProviderLoginView()
    }

    // 2. ログインボタンの配置
    func setupProviderLoginView() {
      let authorizationButton = ASAuthorizationAppleIDButton()
      authorizationButton.addTarget(self, action: #selector(handleAuthorizationAppleIDButtonPress), for: .touchUpInside)
      self.stackView.addArrangedSubview(authorizationButton)
    }
    
    // 3. 認証リクエスト
    @objc
    func handleAuthorizationAppleIDButtonPress() {
        // ASAuthorizationAppleIDRequestの作成
        let request = ASAuthorizationAppleIDProvider().createRequest()
        // Scopeの設定
        request.requestedScopes = [.email, .fullName]
        // ASAuthorizationControllerの作成
        let controller = ASAuthorizationController(authorizationRequests: [request])
        // Delegateの設定
        controller.delegate = self
        controller.presentationContextProvider = self
        // 認証リクエストを実行
        controller.performRequests()
    }

}

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

// 4. ハンドリング
extension ViewController: ASAuthorizationControllerDelegate {
    func authorizationController(controller: ASAuthorizationController, didCompleteWithAuthorization authorization: ASAuthorization) {

        if let appleIDCredential = authorization.credential as? ASAuthorizationAppleIDCredential {
            guard
                let authCodeData = appleIDCredential.authorizationCode,
                let authCode = String(data: authCodeData, encoding: .utf8),
                let idTokenData = appleIDCredential.identityToken,
                let idToken = String(data: idTokenData, encoding: .utf8),
                let fullName = appleIDCredential.fullName else {
                print("Problem with the authorizationCode")
                return
            }
            print("authorization code : \(authCode)")
            print("identity token : \(idToken)")
            print("full name : \(fullName)")

        }
    }

    func authorizationController(controller: ASAuthorizationController, didCompleteWithError error: Error) {
        print("Authorization Failed: \(error)")
    }
}

// ASAuthorizationAppleIDRequestの作成
let request = ASAuthorizationAppleIDProvider().createRequest()
// Scopeの設定
request.requestedScopes = [.email, .fullName]
// ASAuthorizationControllerの作成
let controller = ASAuthorizationController(authorizationRequests: [request])
// Delegateの設定
controller.delegate = self
controller.presentationContextProvider = self
// 認証リクエストを実行
controller.performRequests()

{
  "iss": "https://appleid.apple.com",
  "aud": "jp.classmethod.siwa",
  "exp": 1571152178,
  "iat": 1571151578,
  "sub": "000856.7b04d71ac07a425ab7dfa0972216efd8.1358",
  "c_hash": "7JcWQaa6H4EtW202BB_f-w",
  "email": "fxn4uvrw9g@privaterelay.appleid.com",
  "email_verified": "true",
  "is_private_email": "true",
  "auth_time": 1571151578
}