Sign In with Apple: How to achieve it for existing app?

Question

With recent major updates released by Apple on 3rd June 2019, there is one feature Sign In with Apple. Information about 'how to use this' in app is available but I can see any sample source code, how to achieve this feature in your existing iOS app.

I'm looking for a sample source code, as I can't understand how to start with this.

And what I've tried: Sign In with Apple

Answer 1

First step is you need to import AuthenticationServices

How to check that user credential state

        let appleIDProvider = ASAuthorizationAppleIDProvider()
        appleIDProvider.getCredentialState(forUserID: KeychainItem.currentUserIdentifier) { (credentialState, error) in
            switch credentialState {
            case .authorized:
                // The Apple ID credential is valid.
                break
            case .revoked:
                // The Apple ID credential is revoked.
                break
            case .notFound:
                // No credential was found, so show the sign-in UI.
               
            default:
                break
            }
        }

How to create Login with Apple

Step1

Prompts the user if an existing iCloud Keychain credential or Apple ID credential is found. implement ASAuthorizationControllerDelegate to

func performExistingAccountSetupFlows() {
    // Prepare requests for both Apple ID and password providers.
    let requests = [ASAuthorizationAppleIDProvider().createRequest(),
                    ASAuthorizationPasswordProvider().createRequest()]
    
    // Create an authorization controller with the given requests.
    let authorizationController = ASAuthorizationController(authorizationRequests: requests)
    authorizationController.delegate = self
    authorizationController.presentationContextProvider = self
    authorizationController.performRequests()
}

extension ViewController: ASAuthorizationControllerDelegate {
    func authorizationController(controller: ASAuthorizationController, didCompleteWithAuthorization authorization: ASAuthorization) {
        if let appleIDCredential = authorization.credential as? ASAuthorizationAppleIDCredential {
         //here is credentials . 
        }
    }
}

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

Step2:

create button

    let authorizationButton = ASAuthorizationAppleIDButton()
    authorizationButton.addTarget(self, action: #selector(handleAuthorizationAppleIDButtonPress), for: .touchUpInside)

Step3

@objc
func handleAuthorizationAppleIDButtonPress() {
    let appleIDProvider = ASAuthorizationAppleIDProvider()
    let request = appleIDProvider.createRequest()
    request.requestedScopes = [.fullName, .email]
    
    let authorizationController = ASAuthorizationController(authorizationRequests: [request])
    authorizationController.delegate = self
    authorizationController.presentationContextProvider = self
    authorizationController.performRequests()
}

Availability : iOS 13 or higher

Demo Application: A complete working demo application with keychain integration available on Github - https://github.com/developerinsider/Sign-In-with-Apple-Demo

Note: I will update answer with more and more useful information soon.

Hope it is helpful .