🍏 + 🔥 = ❤️ (Firebase for Apple Developers)

In this talk, I am going to walk you through the building blocks for creating modern applications on Apple’s platforms using SwiftUI and Firebase.

We will cover the following topics:

- Setting up an architecture for data-driven applications
- What’s new in SwiftUI’s application life cycle
- Syncing data in realtime across multiple devices with Cloud Firestore
- Mapping Firestore documents in a type-safe way using the Codable protocol
- Using Combine to fetch data from remote APIs and Firebase
- How async/await (new in Swift 5.5) will affect the way we write asynchronous code (plus some surprises in Firebase's code base)

Firebase is always evolving, so I will also talk about how we’re making use of Apple’s latest technologies in our own code base, for example

- Combine
- async/await
- SwiftUI view modifiers

No matter if you’re a seasoned Firebase user or just wondering what it is all about, you should leave this session with a deeper understanding of what Firebase it and how you can use it your apps on Apple’s platforms.

Transcript

1. Peter Friese | Firebase Developer Advocate | @pete rf riese  + Firebase for Apple Developers
2. Architecture Swi ft UI 2 Life Cycle Firebase Firestore Authentication Combine async/await Completion block
3. Architecture For Data-Driven Apps Photo by Lance Anderson on Unsplash
4. #one-book-a-week-challenge
6. Drill-down navigation Three-column layout (iPad / Mac) Single source of truth Driving factors UI always in sync
7. UI always in sync
8. BookShelfView BookEditView BookDetailsView BookRowView Source of Truth books: [Book] @ObservableObject @Binding Book Book Book
9. Challenge #1 This needs to be a binding But this isn’t a list of bindings
10. struct BookShelfView: View { @Binding var bookShelf: BookShelf var body: some View { List { ForEach(Array(bookShelf.books.enumerated()), id: \.element.id) { index, item in BookRowView(book: $bookShelf.books[index]) } .onDelete { indexSet in bookShelf.books.remove(atOffsets: indexSet) } } .navigationTitle(bookShelf.title) } } Solution #1: iterate over enumerated items 🤔
11. struct BookShelfView: View { @Binding var bookShelf: BookShelf var body: some View { List { ForEach($bookShelf.books) { $book in BookRowView(book: $book) } .onDelete { indexSet in bookShelf.books.remove(atOffsets: indexSet) } } .navigationTitle(bookShelf.title) } } Solution #1: use list bindings Everything is now bindable
12. Learn more h tt ps://pete rf riese.dev/swi ft ui-list-item-bindings-behind-the-scenes/
13. How to update only when the user commits? Challenge #2
14. struct BookEditView: View { @Binding var book: Book @ObservedObject var bookEditViewModel: BookEditViewModel init(book: Binding<Book>) { self._book = book self.bookEditViewModel = BookEditViewModel(book: book.wrappedValue) } var body: some View { TextField("Book title", text: $bookEditViewModel.book.title) } func save() { self.book = bookEditViewModel.book dismiss() } } Solution 2: use inner @ObservableObject
15. struct BookEditView: View { @Binding var book: Book @ObservedObject var bookEditViewModel: BookEditViewModel init(book: Binding<Book>) { self._book = book self.bookEditViewModel = BookEditViewModel(book: book.wrappedValue) } var body: some View { TextField("Book title", text: $bookEditViewModel.book.title) } func save() { self.book = bookEditViewModel.book dismiss() } } Solution 2: use inner @ObservableObject
16. struct BookEditView: View { @Binding var book: Book @ObservedObject var bookEditViewModel: BookEditViewModel init(book: Binding<Book>) { self._book = book self.bookEditViewModel = BookEditViewModel(book: book.wrappedValue) } var body: some View { TextField("Book title", text: $bookEditViewModel.book.title) } func save() { self.book = bookEditViewModel.book dismiss() } } Solution 2: use inner @ObservableObject
17. struct BookEditView: View { @Binding var book: Book @ObservedObject var bookEditViewModel: BookEditViewModel init(book: Binding<Book>) { self._book = book self.bookEditViewModel = BookEditViewModel(book: book.wrappedValue) } var body: some View { TextField("Book title", text: $bookEditViewModel.book.title) } func save() { self.book = bookEditViewModel.book dismiss() } } Solution 2: use inner @ObservableObject
18. Solution 2
19. class BookEditViewModel: ObservableObject { @Published var book: Book @Published var isISBNValid: Bool = true init(book: Book) { self.book = book self.$book .map { checkISBN(isbn: $0.isbn) } .assign(to: &$isISBNValid) } } Solution 2: use inner @ObservableObject Bonus: use Combine to perform validation
20. Learn more about Building SwiftUI Components h tt ps://www.youtube.com/c/pete rf riese
21. Architecture Swi ft UI 2 Life Cycle Firebase Firestore Authentication Combine async/await Completion block
23. Run with confidence Engage users Develop apps faster
24. Run with confidence Crashlytics Performance Monitoring Test Lab App Distribution Engage users Analytics Predictions Cloud Messaging Remote Config A/B Testing Dynamic Links In-app Messaging Develop apps faster Auth Cloud Functions Cloud Firestore Hosting ML Kit Realtime Database Cloud Storage bit.ly/what-is-firebase Extensions Machine Learning
28. #protip: Put it beneath Asset.xcasset
29. Don’t forget to add to all the targets!
30. Swift Package Manager now officially supported! h tt ps://github.com/ fi rebase/ fi rebase-ios-sdk
31. 🤔
32. Application Lifecycle SwiftUI 2 Photo by Thor Alvis on Unsplash
33. SwiftUI 2: No more AppDelegate! import SwiftUI @main struct BookShelfApp: App { @StateObject var store = BookShelfStore(shelves: BookShelf.samples) var body: some Scene { WindowGroup { NavigationView { BookShelvesView(store: store) Text("Select a shelf to see its books") Text("Select a book to see its details") } } } }
34. SwiftUI 2: No more AppDelegate! import SwiftUI @main struct BookShelfApp: App { @StateObject var store = BookShelfStore(shelves: BookShelf.samples) var body: some Scene { WindowGroup { NavigationView { BookShelvesView(store: store) Text("Select a shelf to see its books") Text("Select a book to see its details") } } } }
35. Solution 1: use initialiser import SwiftUI @main struct BookShelfApp: App { @StateObject var store = BookShelfStore(shelves: BookShelf.samples) var body: some Scene { WindowGroup { NavigationView { BookShelvesView(store: store) Text("Select a shelf to see its books") Text("Select a book to see its details") }
36. Solution 1: use initialiser import SwiftUI @main struct BookShelfApp: App { @StateObject var store = BookShelfStore(shelves: BookShelf.samples) var body: some Scene { WindowGroup { NavigationView { BookShelvesView(store: store) Text("Select a shelf to see its books") Text("Select a book to see its details") } init() { FirebaseApp.configure() }
37. Solution 2: use UIApplicationDelegateAdaptor import SwiftUI import Firebase class AppDelegate: NSObject, UIApplicationDelegate { func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) - > Bool { FirebaseApp.configure() return true } } @main struct BookShelfApp: App { @UIApplicationDelegateAdaptor(AppDelegate.self) var delegate
38. Solution 2: use UIApplicationDelegateAdaptor import SwiftUI import Firebase class AppDelegate: NSObject, UIApplicationDelegate { func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) - > Bool { FirebaseApp.configure() return true } } @main struct BookShelfApp: App { @UIApplicationDelegateAdaptor(AppDelegate.self) var delegate
39. Solution 2: use UIApplicationDelegateAdaptor import SwiftUI import Firebase class AppDelegate: NSObject, UIApplicationDelegate { func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) - > Bool { FirebaseApp.configure() return true } } @main struct BookShelfApp: App { @UIApplicationDelegateAdaptor(AppDelegate.self) var delegate
40. Solution 2: use UIApplicationDelegateAdaptor import SwiftUI import Firebase class AppDelegate: NSObject, UIApplicationDelegate { func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) - > Bool { FirebaseApp.configure() return true } } @main struct BookShelfApp: App { @UIApplicationDelegateAdaptor(AppDelegate.self) var delegate
41. Watch the scene phase Handle deep links Continue user activities Do more with the new life cycle
42. Watch the scene phase Handle deep links Continue user activities Learn more pete rf riese.dev/ultimate-guide-to-swi ft ui2-application-lifecycle/
43. Architecture Swi ft UI 2 Life Cycle Firebase Firestore Authentication Combine async/await Completion block
44. Firestore
47. One-Time Fetches Offline Mode Effortless Syncing
48. bird_type: airspeed: coconut_capacity: isNative: icon: vector: distances_traveled: "swallow" 42.733 0.62 false <binary data> { x: 36.4255, y: 25.1442, z: 18.8816 } [42, 39, 12, 42] Document
49. Collection Sub-Collection
50. Top level collections “books” collection a single book document
51. struct Book: Identifiable { var id = UUID().uuidString var shelfId: String? var userId: String? var title: String var author: String var isbn: String var pages: Int var isRead: Bool = false var coverEditionKey: String? } Data Model
52. func fetchBook(documentId: String) { let docRef = Firestore.firestore().collection("books").document(documentId) docRef.getDocument { document, error in if let error = error as NSError? { print("Error getting document: \(error.localizedDescription)") } else { if let document = document { let id = document.documentID let data = document.data() let title = data?["title"] as? String ?? "" let numberOfPages = data?["numberOfPages"] as? Int ?? 0 let author = data?["author"] as? String ? ? "" self.book = Book(id:id, title: title, numberOfPages: numberOfPages, author: author) } } } } Fetching a document from Firestore
53. func fetchBook(documentId: String) { let docRef = Firestore.firestore().collection("books").document(documentId) docRef.getDocument { document, error in if let error = error as NSError? { print("Error getting document: \(error.localizedDescription)") } else { if let document = document { let id = document.documentID let data = document.data() let title = data?["title"] as? String ?? "" let numberOfPages = data?["numberOfPages"] as? Int ?? 0 let author = data?["author"] as? String ? ? "" self.book = Book(id:id, title: title, numberOfPages: numberOfPages, author: author) } } } } Fetching a document from Firestore
54. func fetchBook(documentId: String) { let docRef = Firestore.firestore().collection("books").document(documentId) docRef.getDocument { document, error in if let error = error as NSError? { print("Error getting document: \(error.localizedDescription)") } else { if let document = document { let id = document.documentID let data = document.data() let title = data?["title"] as? String ?? "" let numberOfPages = data?["numberOfPages"] as? Int ?? 0 let author = data?["author"] as? String ? ? "" self.book = Book(id:id, title: title, numberOfPages: numberOfPages, author: author) } } } } Fetching a document from Firestore
55. func fetchBook(documentId: String) { let docRef = Firestore.firestore().collection("books").document(documentId) docRef.getDocument { document, error in if let error = error as NSError? { print("Error getting document: \(error.localizedDescription)") } else { if let document = document { let id = document.documentID let data = document.data() let title = data?["title"] as? String ?? "" let numberOfPages = data?["numberOfPages"] as? Int ?? 0 let author = data?["author"] as? String ? ? "" self.book = Book(id:id, title: title, numberOfPages: numberOfPages, author: author) } } } } Fetching a document from Firestore
56. func fetchBook(documentId: String) { let docRef = Firestore.firestore().collection("books").document(documentId) docRef.getDocument { document, error in if let error = error as NSError? { print("Error getting document: \(error.localizedDescription)") } else { if let document = document { let id = document.documentID let data = document.data() let title = data?["title"] as? String ?? "" let numberOfPages = data?["numberOfPages"] as? Int ?? 0 let author = data?["author"] as? String ? ? "" self.book = Book(id:id, title: title, numberOfPages: numberOfPages, author: author) } } } } Fetching a document from Firestore
57. func fetchBook(documentId: String) { let docRef = Firestore.firestore().collection("books").document(documentId) docRef.getDocument { document, error in if let error = error as NSError? { print("Error getting document: \(error.localizedDescription)") } else { if let document = document { let id = document.documentID let data = document.data() let title = data?["title"] as? String ?? "" let numberOfPages = data?["numberOfPages"] as? Int ?? 0 let author = data?["author"] as? String ? ? "" self.book = Book(id:id, title: title, numberOfPages: numberOfPages, author: author) } } } } Fetching a document from Firestore
58. func fetchBook(documentId: String) { let docRef = Firestore.firestore().collection("books").document(documentId) docRef.getDocument { document, error in if let error = error as NSError? { print("Error getting document: \(error.localizedDescription)") } else { if let document = document { let id = document.documentID let data = document.data() let title = data?["title"] as? String ?? "" let numberOfPages = data?["numberOfPages"] as? Int ?? 0 let author = data?["author"] as? String ? ? "" self.book = Book(id:id, title: title, numberOfPages: numberOfPages, author: author) } } } } Fetching a document from Firestore if let document = document { let id = document.documentID let data = document.data() let title = data?["title"] as? String ?? "" let numberOfPages = data?["numberOfPages"] as? Int ?? 0 let author = data?["author"] as? String ? ? "" self.book = Book(id:id, title: title, numberOfPages: numberOfPages, author: author) } Can we do better?
59. (Yes, we can)
60. func fetchBook(documentId: String) { let docRef = Firestore.firestore().collection("books").document(documentId) docRef.getDocument { document, error in if let error = error as NSError? { print("Error getting document: \(error.localizedDescription)") } else { if let document = document { let id = document.documentID let data = document.data() let title = data?["title"] as? String ?? "" let numberOfPages = data?["numberOfPages"] as? Int ?? 0 let author = data?["author"] as? String ? ? "" self.book = Book(id:id, title: title, numberOfPages: numberOfPages, author: author) } } } } Fetching a document from Firestore
61. func fetchBook(documentId: String) { let docRef = Firestore.firestore().collection("books").document(documentId) docRef.getDocument { document, error in if let error = error as NSError? { print("Error getting document: \(error.localizedDescription)") } else { } } } Mapping data using Codable if let document = document { do { self.book = try document.data(as: Book.self) } catch { print(error) } }
62. func fetchBook(documentId: String) { let docRef = Firestore.firestore().collection("books").document(documentId) docRef.getDocument { document, error in if let error = error as NSError? { print("Error getting document: \(error.localizedDescription)") } else { } } } Mapping data using Codable if let document = document { do { self.book = try document.data(as: Book.self) } catch { print(error) } }
63. BookShelfView BookEditView BookDetailsView BookRowView Source of Truth books: [Book] @ObservableObject @Binding Book Book Book Review: Architecture
64. BookShelfView BookDetailsView BookRowView Source of Truth books: [Book] @ObservableObject @Binding Book Book Review: Architecture Snapshot Listener
65. class BookStore: ObservableObject { var db = Firestore.firestore() private var listenerRegistration: ListenerRegistration? @Published var books = [Book]() func subscribe() { listenerRegistration = db.collection("books") .addSnapshotListener { [weak self] (querySnapshot, error) in guard let documents = querySnapshot ?. documents else { return } self ?. books = documents.compactMap { queryDocumentSnapshot in let result = Result { try queryDocumentSnapshot.data(as: Book.self) } switch result { case .success(let book): if let book = book { return book Fetching a collection of documents
66. class BookStore: ObservableObject { var db = Firestore.firestore() private var listenerRegistration: ListenerRegistration? @Published var books = [Book]() func subscribe() { listenerRegistration = db.collection("books") .addSnapshotListener { [weak self] (querySnapshot, error) in guard let documents = querySnapshot ?. documents else { return } self ?. books = documents.compactMap { queryDocumentSnapshot in let result = Result { try queryDocumentSnapshot.data(as: Book.self) } switch result { case .success(let book): if let book = book { return book Fetching a collection of documents
67. class BookStore: ObservableObject { var db = Firestore.firestore() private var listenerRegistration: ListenerRegistration? @Published var books = [Book]() func subscribe() { listenerRegistration = db.collection("books") .addSnapshotListener { [weak self] (querySnapshot, error) in guard let documents = querySnapshot ?. documents else { return } self ?. books = documents.compactMap { queryDocumentSnapshot in let result = Result { try queryDocumentSnapshot.data(as: Book.self) } switch result { case .success(let book): if let book = book { return book Fetching a collection of documents
68. class BookStore: ObservableObject { var db = Firestore.firestore() private var listenerRegistration: ListenerRegistration? @Published var books = [Book]() func subscribe() { listenerRegistration = db.collection("books") .addSnapshotListener { [weak self] (querySnapshot, error) in guard let documents = querySnapshot ?. documents else { return } self ?. books = documents.compactMap { queryDocumentSnapshot in let result = Result { try queryDocumentSnapshot.data(as: Book.self) } switch result { case .success(let book): if let book = book { return book Fetching a collection of documents
69. class BookStore: ObservableObject { var db = Firestore.firestore() private var listenerRegistration: ListenerRegistration? @Published var books = [Book]() func subscribe() { listenerRegistration = db.collection("books") .addSnapshotListener { [weak self] (querySnapshot, error) in guard let documents = querySnapshot ?. documents else { return } self ?. books = documents.compactMap { queryDocumentSnapshot in let result = Result { try queryDocumentSnapshot.data(as: Book.self) } switch result { case .success(let book): if let book = book { return book Fetching a collection of documents
70. class BookStore: ObservableObject { var db = Firestore.firestore() private var listenerRegistration: ListenerRegistration? @Published var books = [Book]() func subscribe() { listenerRegistration = db.collection("books") .addSnapshotListener { [weak self] (querySnapshot, error) in guard let documents = querySnapshot ?. documents else { return } self ?. books = documents.compactMap { queryDocumentSnapshot in let result = Result { try queryDocumentSnapshot.data(as: Book.self) } switch result { case .success(let book): if let book = book { return book Fetching a collection of documents
71. class BookStore: ObservableObject { var db = Firestore.firestore() private var listenerRegistration: ListenerRegistration? @Published var books = [Book]() func subscribe() { listenerRegistration = db.collection("books") .addSnapshotListener { [weak self] (querySnapshot, error) in guard let documents = querySnapshot ?. documents else { return } self ?. books = documents.compactMap { queryDocumentSnapshot in let result = Result { try queryDocumentSnapshot.data(as: Book.self) } switch result { case .success(let book): if let book = book { return book Fetching a collection of documents
73. Learn more h tt ps://pete rf riese.dev/ fi restore-codable-the-comprehensive-guide/
74. import Foundation import Combine import Firebase import FirebaseFirestoreSwift import os class BookStore: ObservableObject { // MARK: - Dependencies var db = Firestore.firestore() // MARK: - Publishers @Published var user: User? @Published var books = [Book]() // MARK: - Private attributes @Published private var userId: String = "unknown" private var listenerRegistration: ListenerRegistration? private var cancellables = Set<AnyCancellable>() Fetching a collection of documents
75. // A Book value could not be initialized from the DocumentSnapshot. switch error { case DecodingError.typeMismatch(_, let context): self ? . logger.debug("\(error.localizedDescription): \ (context.debugDescription)") case DecodingError.valueNotFound(_, let context): self ? . logger.debug("\(error.localizedDescription): \ (context.debugDescription)") case DecodingError.keyNotFound(_, let context): self ? . logger.debug("\(error.localizedDescription): \ (context.debugDescription)") case DecodingError.dataCorrupted(let key): self ? . logger.debug("\(error.localizedDescription): \ (key.debugDescription)") default: self ? . logger.debug("Error decoding document: \ (error.localizedDescription)") } return nil } } } } Fetching a collection of documents
76. // A Book value could not be initialized from the DocumentSnapshot. switch error { case DecodingError.typeMismatch(_, let context): self ? . logger.debug("\(error.localizedDescription): \ (context.debugDescription)") case DecodingError.valueNotFound(_, let context): self ? . logger.debug("\(error.localizedDescription): \ (context.debugDescription)") case DecodingError.keyNotFound(_, let context): self ? . logger.debug("\(error.localizedDescription): \ (context.debugDescription)") case DecodingError.dataCorrupted(let key): self ? . logger.debug("\(error.localizedDescription): \ (key.debugDescription)") default: self ? . logger.debug("Error decoding document: \ (error.localizedDescription)") } return nil } } } } Fetching a collection of documents about 100 lines of code
77. struct BookShelfView: View { @FirestoreQuery( collectionPath: "books", predicates: [ .where("userId", isEqualTo: userId), ] ) var books: Result<[Book], Error> @State var userId = "F18EBA5E" var body: some View { List(books) { book in Text(book.title) } } } Firestore Property Wrapper Firebase 8.9.0 @FloWritesCode @mo rt enditlevsen Thanks to
78. Architecture Swi ft UI 2 Life Cycle Firebase Firestore Authentication Combine async/await Completion block
79. Authentication Photo by Conve rt Kit on Unsplash
80. Authentication Photo by Eduardo Soares on Unsplash
81. Authentication Photo by Victor Freitas on Unsplash
82. 
83. Sign in the user Update the data model Secure users’ data How to implement Firebase Authentication?
84. Anonymous Authentication “Guest” accounts, rather
85. func signIn() { registerStateListener() if Auth.auth().currentUser == nil { Auth.auth().signInAnonymously() } } Anonymous Authentication
87. SignInWithAppleButton( onRequest: { .. . }, onCompletion: { result in ... let appleIDToken = appleIDCredential.identityToken let idTokenString = String(data: appleIDToken, encoding: .utf8) let credential = OAuthProvider.credential(withProviderID: “apple.com", idToken: idTokenString, rawNonce: nonce) Auth.auth().signIn(with: credential) { (authResult, error) in if (error ! = nil) { .. . } print(“User signed in") dismiss() } } ).frame(width: 280, height: 45, alignment: .center) Sign in with Apple
88. SignInWithAppleButton( onRequest: { .. . }, onCompletion: { result in ... let appleIDToken = appleIDCredential.identityToken let idTokenString = String(data: appleIDToken, encoding: .utf8) let credential = OAuthProvider.credential(withProviderID: “apple.com", idToken: idTokenString, rawNonce: nonce) Auth.auth().signIn(with: credential) { (authResult, error) in if (error ! = nil) { .. . } print(“User signed in") dismiss() } } ).frame(width: 280, height: 45, alignment: .center) Sign in with Apple
89. SignInWithAppleButton( onRequest: { .. . }, onCompletion: { result in ... let appleIDToken = appleIDCredential.identityToken let idTokenString = String(data: appleIDToken, encoding: .utf8) let credential = OAuthProvider.credential(withProviderID: “apple.com", idToken: idTokenString, rawNonce: nonce) Auth.auth().signIn(with: credential) { (authResult, error) in if (error ! = nil) { .. . } print(“User signed in") dismiss() } } ).frame(width: 280, height: 45, alignment: .center) Sign in with Apple
90. SignInWithAppleButton( onRequest: { .. . }, onCompletion: { result in ... let appleIDToken = appleIDCredential.identityToken let idTokenString = String(data: appleIDToken, encoding: .utf8) let credential = OAuthProvider.credential(withProviderID: “apple.com", idToken: idTokenString, rawNonce: nonce) Auth.auth().signIn(with: credential) { (authResult, error) in if (error ! = nil) { .. . } print(“User signed in") dismiss() } } ).frame(width: 280, height: 45, alignment: .center) Sign in with Apple
91. SignInWithAppleButton( onRequest: { .. . }, onCompletion: { result in ... let appleIDToken = appleIDCredential.identityToken let idTokenString = String(data: appleIDToken, encoding: .utf8) let credential = OAuthProvider.credential(withProviderID: “apple.com", idToken: idTokenString, rawNonce: nonce) Auth.auth().signIn(with: credential) { (authResult, error) in if (error ! = nil) { .. . } print(“User signed in") dismiss() } } ).frame(width: 280, height: 45, alignment: .center) Sign in with Apple Firebase SDK
92. SignInWithAppleButton( onRequest: { .. . }, onCompletion: { result in ... let appleIDToken = appleIDCredential.identityToken let idTokenString = String(data: appleIDToken, encoding: .utf8) let credential = OAuthProvider.credential(withProviderID: “apple.com", idToken: idTokenString, rawNonce: nonce) Auth.auth().signIn(with: credential) { (authResult, error) in if (error ! = nil) { .. . } print(“User signed in") dismiss() } } ).frame(width: 280, height: 45, alignment: .center) Sign in with Apple Firebase SDK
93. All books are stored in one single collection Which user do they belong to?
94. let query = db.collection("books") .whereField("userId", isEqualTo: self.userId) query .addSnapshotListener { [weak self] (querySnapsho guard let documents = querySnapshot ?. documents els Signed in user
95. rules_version = '2'; service cloud.firestore { match /databases/{database}/documents { match /{document=**} { allow create: if request.auth != null; allow read, update, delete: if request.auth != null && resource.data.userId = = request.auth.uid; } } } Security Rules Only signed-in users can create new documents Only owners may read and modify a document
96. Architecture Swi ft UI 2 Life Cycle Firebase Firestore Authentication Combine async/await Completion block
97. Combine
98. auth ?. signInAnonymously() let user = auth ?. currentUser print("User signed in with user ID: \(user ? . uid)") This might be nil
99. auth ?. signInAnonymously() let user = auth ?. currentUser print("User signed in with user ID: \(user ? . uid)") auth ?. signInAnonymously { result, error in guard let result = result else { return } print("User signed in with user ID: \(result.user.uid)") } Do this instead
100. auth . .. auth ?. signInAnonymously() .map{ $0.user } .replaceError(with: nil) .assign(to: &$user) Even better
101. Launching with Firebase 8.9.0 h tt ps://github.com/ fi rebase/ fi rebase-ios-sdk/projects/3
102. Architecture Swi ft UI 2 Life Cycle Firebase Firestore Authentication Combine async/await Completion block
103. async/await Photo by Stephen H on Unsplash
104. extension ArticleAnalyser { func process(url: String, completion: @escaping (Article) -> Void) { self.fetchArticle(from: url) { result in switch result { case .failure(let error): print(error.localizedDescription) case .success(let html): self.extractTitle(from: html) { result in switch result { case .failure(let error): print(error.localizedDescription) case .success(let title): self.extractText(from: html) { result in switch result { case .failure(let error): print(error.localizedDescription) case .success(let text): self.extractImage(from: url) { result in Problem: Callback Pyramid of Doom
105. extension AsyncArticleAnalyser { func process(url: String) async throws -> Article { let htmlText = try await fetchArticle(from: url) let text = try await extractText(from: htmlText) let title = try await extractTitle(from: htmlText) let imageUrl = try await extractImage(from: url) let tags = await inferTags(from: text) return Article(url: url, title: title, tags: tags, imageUrlString: imageUrl) } } Solution: Use async/await Swift 5.5
106. func fetchArticle(from url: String) async throws -> String { guard let url = URL(string: url) else { throw AnalyserError.badURL } return try await withUnsafeThrowingContinuation { continuation in URLSession.shared.downloadTask(with: url) { (localUrl, urlResponse, error) in guard let localUrl = localUrl else { continuation.resume(throwing: AnalyserError.badURL) return } if let htmlText = try? String(contentsOf: localUrl) { continuation.resume(returning: htmlText) } } .resume() } } Solution: Use async/await Swift 5.5
107. func fetchArticle(from url: String) async throws -> String { guard let url = URL(string: url) else { throw AnalyserError.badURL } return try await withUnsafeThrowingContinuation { continuation in URLSession.shared.downloadTask(with: url) { (localUrl, urlResponse, error) in guard let localUrl = localUrl else { continuation.resume(throwing: AnalyserError.badURL) return } if let htmlText = try? String(contentsOf: localUrl) { continuation.resume(returning: htmlText) } } .resume() } } Solution: Use async/await Swift 5.5
108. func fetchArticle(from url: String) async throws -> String { guard let url = URL(string: url) else { throw AnalyserError.badURL } return try await withUnsafeThrowingContinuation { continuation in URLSession.shared.downloadTask(with: url) { (localUrl, urlResponse, error) in guard let localUrl = localUrl else { continuation.resume(throwing: AnalyserError.badURL) return } if let htmlText = try? String(contentsOf: localUrl) { continuation.resume(returning: htmlText) } } .resume() } } Solution: Use async/await Swift 5.5
109. func fetchArticle(from url: String) async throws -> String { guard let url = URL(string: url) else { throw AnalyserError.badURL } return try await withUnsafeThrowingContinuation { continuation in URLSession.shared.downloadTask(with: url) { (localUrl, urlResponse, error) in guard let localUrl = localUrl else { continuation.resume(throwing: AnalyserError.badURL) return } if let htmlText = try? String(contentsOf: localUrl) { continuation.resume(returning: htmlText) } } .resume() } } Solution: Use async/await Swift 5.5
110. auth ?. signInAnonymously { result, error in guard let result = result else { return } print("User signed in with user ID: \(result.user.uid)") } do { let result = try await Auth.auth().signIn(withEmail: email, password: password) print("User signed in with user ID: \(result.user.uid)") } catch { print(error) } Works with Firebase, too! Callback-style
111. Learn more h tt ps://pete rf riese.dev/async-await-in-swi f h tt ps://www.youtube.com/watch?v=sEKw2BMcQtQ
112. Architecture Swi ft UI 2 Life Cycle Firebase Firestore Authentication Combine async/await Completion block
113. Architecture Swi ft UI 2 Life Cycle Firebase Firestore Authentication Combine async/await Completion block
114. Register now - it’s free! h tt ps:// fi rebase.google.com/summit
115. Thanks! Peter Friese h tt p://pete rf riese.dev @pete rf riese 
 youtube.com/c/PeterFriese/ Follow me h tt ps://github.com/pete rf riese/BookShelf Code
116. Credits fi nish by Megan Chown from the Noun Project Time by Nikita Kozin from the Noun Project pipe by Komkrit Noenpoempisut from the Noun Project Passpo rt by ProSymbols from the Noun Project spiral by Alexander Skowalsky from the Noun Project Architecture by Ervin Bolat from the Noun Project Firebase logos cou rt esy h tt ps:// fi rebase.google.com/brand-guidelines Firebase logos cou rt esy h tt ps:// fi rebase.google.com/brand-guidelines Thanks! Hea rt by Roman from the Noun Project
117. The End.