Implementing Apple Sign-In to an iOS App

Introduction

The Apple Sign-In feature is very helpful and offers users login functionality with one click. It could be highly beneficial from a business perspective to attract more potential customers by providing easy and secure access to application functionality. In this article, I will focus on how to implement Apple Sign-In.

Before implementation, let’s set up the necessary options to be able to run the app without errors.

Add Sign in with Apple Capability to the project

📝 Before testing on the simulator, you need to be signed in to an account with enabled two-factor authentication.

Apple offers a built-in solution that uses the Authentication Services framework with ASAuthorizationAppleIDButton.

First Step

The first step is to set up the Sign-In button.

func setupAppleIDButton() {
    let authButton = ASAuthorizationAppleIDButton()
    authButton.frame = CGRect(origin: view.center, size: CGSize(width: 128, height: 56))
    authButton.addTarget(self, action: #selector(handleAuthorizationAppleIDButtonPress), for: .touchUpInside)
    view.addSubview(authButton)
}

💡 ASAuthorizationAppleIDButton - A control that enables users to initiate the Sign In with Apple flow.

Second Step

The second step is to handle the authorization Apple ID button press.

@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()
}

💡 ASAuthorizationAppleIDProvider - A mechanism for generating requests to authenticate users based on their Apple ID.

💡 ASAuthorizationController - A controller that manages authorization requests that a provider creates.

Third Step

The third step is to implement authorizationController.delegate and authorizationController.presentationContextProvider.

// MARK: - ASAuthorizationControllerDelegate
extension LoginViewController: ASAuthorizationControllerDelegate {
    /// - Tag: did_complete_authorization
    public func authorizationController(controller _: ASAuthorizationController, didCompleteWithAuthorization authorization: ASAuthorization) {
        switch authorization.credential {
        case let appleIDCredential as ASAuthorizationAppleIDCredential:

            // Create an account in your system.
            let userIdentifier = appleIDCredential.user
            let fullName = appleIDCredential.fullName
            let email = appleIDCredential.email

        case let passwordCredential as ASPasswordCredential:

            // Sign in using an existing iCloud Keychain credential.
            let username = passwordCredential.user
            let password = passwordCredential.password

        default:
            break
        }
    }

    /// - Tag: did_complete_error
    public func authorizationController(controller _: ASAuthorizationController, didCompleteWithError error: any Error) {
        // Handle error.
        print(error)
    }
}

💡 ASAuthorizationControllerDelegate - An interface for providing information about the outcome of an authorization request.

// MARK: - ASAuthorizationControllerPresentationContextProviding
extension LoginViewController: ASAuthorizationControllerPresentationContextProviding {
    /// - Tag: provide_presentation_anchor
    public func presentationAnchor(for _: ASAuthorizationController) -> ASPresentationAnchor {
        view.window!
    }
}

💡 ASAuthorizationControllerPresentationContextProviding - An interface the controller uses to ask a delegate for a presentation context.

Implementing Apple Sign-In to an iOS App

Introduction

First Step

Second Step

Third Step

Resources

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Thank you for reading! 😊

Introduction#