henning-jh

In John Sundell’s excellent article Using child view controllers as plugins in Swift, Mr. Sundell reminds us that Apple has given us the ability to compose UIViewController objects together, allowing multiple controllers to display in one view. He also gave us two helper functions to use, one to add a child view controller and the other to remove it. Here is the the function to add a child controller to another controller:

func add(_ child: UIViewController) {
    addChildViewController(child)
    view.addSubview(child.view)
    child.didMove(toParentViewController: self)
}

henning-jh

Just as a reference, here's a UICollectionView with some nice evenly spaced cells.

class ViewController: UIViewController, UICollectionViewDataSource /*, UICollectionViewDelegate */ {

	let kReuseIdentifier = "CollectionCellID"
	let kNumCellsPerRow:CGFloat = 3.0
	let kSpacer:CGFloat = 10.0
	var collectionView : UICollectionView!
	

henning-jh

import AuthenticationServices

func createButton() {
    let authorizationButton = ASAuthorizationAppleIDButton()
    authorizationButton.addTarget(self, action: 
        #selector(handleAuthorizationAppleIDButtonPress), 
        for: .touchUpInside)
    myView.addSubview(authorizationButton)
}

henning-jh

@objc
func handleAuthorizationAppleIDButtonPress() {
     let request = ASAuthorizationAppleIDProvider().createRequest()
     request.requestedScopes = [.fullName, .email]

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

henning-jh

/// Prompts the user if an existing iCloud Keychain credential or Apple ID credential is found.
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

henning-jh

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

henning-jh

extension MyLoginViewController: ASAuthorizationControllerDelegate {
     func authorizationController(controller: ASAuthorizationController, 
               didCompleteWithError error: Error) {
          // Handle error.
     }
}

henning-jh

extension MyLoginViewController: ASAuthorizationControllerDelegate {
    func authorizationController(controller: ASAuthorizationController,    
                                   didCompleteWithAuthorization authorization: ASAuthorization) {
        if let appleIDCredential = authorization.credential as? ASAuthorizationAppleIDCredential {

            let userIdentifier = appleIDCredential.user
            let fullName = appleIDCredential.fullName
            let email = appleIDCredential.email

            // Now we have the account information.

henning-jh

        let userIdentifier = // get saved userIdentifier - sample app uses Keychain
        appleIDProvider.getCredentialState(forUserID: userIdentifier) { (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:

henning-jh

    let center = NotificationCenter.default
    let name = NSNotification.Name.ASAuthorizationAppleIDProviderCredentialRevoked
    let observer = center.addObserver(forName: name, object: nil, queue: nil) { (notification) in
        // sign user out
        // optionally guide them to sign in again
    }