In this talk, we are 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 - Storing images and other large files in Cloud Storage - Using Firebase in WidgetKit and on watchOS - 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 we 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.

1. Peter Friese | Developer Advocate, Firebase
Charlo!e Liang | So"ware Engineer, Firebase
 +
Firebase for Apple Developers
@charlo!eCLiang @pete#riese

2. Architecture Swi!UI 2 Life Cycle
Firebase Firestore Authentication Combine async/await Completion block
WidgetKit

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"ps://pete#riese.dev/swi!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"ps://www.youtube.com/c/pete#riese

21. Architecture Swi!UI 2 Life Cycle
Firebase Firestore Authentication Combine async/await Completion block
WidgetKit

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"ps://github.com/%rebase/%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#riese.dev/ultimate-guide-to-swi!ui2-application-lifecycle/

43. Architecture Swi!UI 2 Life Cycle
Firebase Firestore Authentication Combine async/await Completion block
WidgetKit

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 = String?
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"ps://pete#riese.dev/%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&enditlevsen
Thanks to

78. Architecture Swi!UI 2 Life Cycle
Firebase Firestore Authentication Combine async/await Completion block
WidgetKit

79. Driving User Engagement
Photo by ROBIN WORRALL on Unsplash

80. Driving User Engagement
Noti%cations Share Extensions WidgetKit

81. Notification Service Extension
Noti%cation Service Extension + Firebase Messaging
Be!er visualisation of noti%cations
Available in watchOS as well

82. Watch the scene phase
Handle deep links
Continue user activities
Learn more
h"ps://%rebase.blog/posts/2019/09/fcm-image-noti%cation

83. Firebase + WidgetKit
Mini travel blog
How to initialise Firebase
How to access Firebase services

84. Post
Image
ShareExtension Widget
iOS App
Architecture

85. class ShareViewController: SLComposeServiceViewController {
override func didSelectPost() {
!" get data from share controller context
Task {
!" write image data to Cloud Storage
let _ = try await ref.putDataAsync(self.imageData as Data)
let url = try await ref.downloadURL()
!" write post data to Firestore
let post = Post(description: description !# "", url: url.absoluteString)
try db.collection("Posts").document("post").setData(from: post)
!" refresh widgets and return to share controller
WidgetCenter.shared.reloadAllTimelines()
extensionContext!$completeRequest(returningItems: [])
}
}
Firebase in a ShareViewController

86. class ShareViewController: SLComposeServiceViewController {
override func didSelectPost() {
!" get data from share controller context
Task {
!" write image data to Cloud Storage
let _ = try await ref.putDataAsync(self.imageData as Data)
let url = try await ref.downloadURL()
!" write post data to Firestore
let post = Post(description: description !# "", url: url.absoluteString)
try db.collection("Posts").document("post").setData(from: post)
!" refresh widgets and return to share controller
WidgetCenter.shared.reloadAllTimelines()
extensionContext!$completeRequest(returningItems: [])
}
}
Firebase in a ShareViewController

87. class ShareViewController: SLComposeServiceViewController {
override func didSelectPost() {
!" get data from share controller context
Task {
!" write image data to Cloud Storage
let _ = try await ref.putDataAsync(self.imageData as Data)
let url = try await ref.downloadURL()
!" write post data to Firestore
let post = Post(description: description !# "", url: url.absoluteString)
try db.collection("Posts").document("post").setData(from: post)
!" refresh widgets and return to share controller
WidgetCenter.shared.reloadAllTimelines()
extensionContext!$completeRequest(returningItems: [])
}
}
Firebase in a ShareViewController

88. class ShareViewController: SLComposeServiceViewController {
override func didSelectPost() {
!" get data from share controller context
Task {
!" write image data to Cloud Storage
let _ = try await ref.putDataAsync(self.imageData as Data)
let url = try await ref.downloadURL()
!" write post data to Firestore
let post = Post(description: description !# "", url: url.absoluteString)
try db.collection("Posts").document("post").setData(from: post)
!" refresh widgets and return to share controller
WidgetCenter.shared.reloadAllTimelines()
extensionContext!$completeRequest(returningItems: [])
}
}
Firebase in a ShareViewController

89. class ShareViewController: SLComposeServiceViewController {
override func didSelectPost() {
!" get data from share controller context
Task {
!" write image data to Cloud Storage
let _ = try await ref.putDataAsync(self.imageData as Data)
let url = try await ref.downloadURL()
!" write post data to Firestore
let post = Post(description: description !# "", url: url.absoluteString)
try db.collection("Posts").document("post").setData(from: post)
!" refresh widgets and return to share controller
WidgetCenter.shared.reloadAllTimelines()
extensionContext!$completeRequest(returningItems: [])
}
}
Firebase in a ShareViewController

90. class ShareViewController: SLComposeServiceViewController {
override func didSelectPost() {
!" get data from share controller context
Task {
!" write image data to Cloud Storage
let _ = try await ref.putDataAsync(self.imageData as Data)
let url = try await ref.downloadURL()
!" write post data to Firestore
let post = Post(description: description !# "", url: url.absoluteString)
try db.collection("Posts").document("post").setData(from: post)
!" refresh widgets and return to share controller
WidgetCenter.shared.reloadAllTimelines()
extensionContext!$completeRequest(returningItems: [])
}
}
Firebase in a ShareViewController

91. Post
Image
ShareExtension Widget
iOS App
Architecture
Post
Image

92. func getTimeline(for configuration: ConfigurationIntent, in context: Context,
completion: @escaping (Timeline<Entry>) !" Void) {
if FirebaseApp.app() !& nil { FirebaseApp.configure() }
Task {
let (image, text) = try await PostRepository.getPost(imageName: “image.png")
let entry = SimpleEntry(
date: Calendar.current.date(byAdding: .minute, value: 15, to: Date())!,
configuration: configuration,
image: image,
text: text
)
let timeline = Timeline(entries: [entry], policy: .atEnd)
completion(timeline)
}
}
Firebase in a Widget

93. func getTimeline(for configuration: ConfigurationIntent, in context: Context,
completion: @escaping (Timeline<Entry>) !" Void) {
if FirebaseApp.app() !& nil { FirebaseApp.configure() }
Task {
let (image, text) = try await PostRepository.getPost(imageName: “image.png")
let entry = SimpleEntry(
date: Calendar.current.date(byAdding: .minute, value: 15, to: Date())!,
configuration: configuration,
image: image,
text: text
)
let timeline = Timeline(entries: [entry], policy: .atEnd)
completion(timeline)
}
}
Firebase in a Widget

94. func getTimeline(for configuration: ConfigurationIntent, in context: Context,
completion: @escaping (Timeline<Entry>) !" Void) {
if FirebaseApp.app() !& nil { FirebaseApp.configure() }
Task {
let (image, text) = try await PostRepository.getPost(imageName: “image.png")
let entry = SimpleEntry(
date: Calendar.current.date(byAdding: .minute, value: 15, to: Date())!,
configuration: configuration,
image: image,
text: text
)
let timeline = Timeline(entries: [entry], policy: .atEnd)
completion(timeline)
}
}
Firebase in a Widget

95. func getTimeline(for configuration: ConfigurationIntent, in context: Context,
completion: @escaping (Timeline<Entry>) !" Void) {
if FirebaseApp.app() !& nil { FirebaseApp.configure() }
Task {
let (image, text) = try await PostRepository.getPost(imageName: “image.png")
let entry = SimpleEntry(
date: Calendar.current.date(byAdding: .minute, value: 15, to: Date())!,
configuration: configuration,
image: image,
text: text
)
let timeline = Timeline(entries: [entry], policy: .atEnd)
completion(timeline)
}
}
Firebase in a Widget

96. func getTimeline(for configuration: ConfigurationIntent, in context: Context,
completion: @escaping (Timeline<Entry>) !" Void) {
if FirebaseApp.app() !& nil { FirebaseApp.configure() }
Task {
let (image, text) = try await PostRepository.getPost(imageName: “image.png")
let entry = SimpleEntry(
date: Calendar.current.date(byAdding: .minute, value: 15, to: Date())!,
configuration: configuration,
image: image,
text: text
)
let timeline = Timeline(entries: [entry], policy: .atEnd)
completion(timeline)
}
}
Firebase in a Widget

97. import FirebaseStorage
import FirebaseStorageSwift
import FirebaseFirestore
import FirebaseFirestoreSwift
struct PostRepository {
static func getPost(imageName: String) async throws !" (UIImage, String) {
let ref = Storage.storage().reference().child(imageName)
let data = try await ref.data(maxSize: 20 * 1024 * 2048)
let image = UIImage(data: data)!
let db = Firestore.firestore()
let docRef = db.collection("Posts").document("post")
let document = try await docRef.getDocument()
let post = try document.data(as: Post.self)
return (image, post.description)
Firebase in a Widget

98. import FirebaseStorage
import FirebaseStorageSwift
import FirebaseFirestore
import FirebaseFirestoreSwift
struct PostRepository {
static func getPost(imageName: String) async throws !" (UIImage, String) {
let ref = Storage.storage().reference().child(imageName)
let data = try await ref.data(maxSize: 20 * 1024 * 2048)
let image = UIImage(data: data)!
let db = Firestore.firestore()
let docRef = db.collection("Posts").document("post")
let document = try await docRef.getDocument()
let post = try document.data(as: Post.self)
return (image, post.description)
Firebase in a Widget

99. import FirebaseStorage
import FirebaseStorageSwift
import FirebaseFirestore
import FirebaseFirestoreSwift
struct PostRepository {
static func getPost(imageName: String) async throws !" (UIImage, String) {
let ref = Storage.storage().reference().child(imageName)
let data = try await ref.data(maxSize: 20 * 1024 * 2048)
let image = UIImage(data: data)!
let db = Firestore.firestore()
let docRef = db.collection("Posts").document("post")
let document = try await docRef.getDocument()
let post = try document.data(as: Post.self)
return (image, post.description)
Firebase in a Widget

100. import FirebaseStorage
import FirebaseStorageSwift
import FirebaseFirestore
import FirebaseFirestoreSwift
struct PostRepository {
static func getPost(imageName: String) async throws !" (UIImage, String) {
let ref = Storage.storage().reference().child(imageName)
let data = try await ref.data(maxSize: 20 * 1024 * 2048)
let image = UIImage(data: data)!
let db = Firestore.firestore()
let docRef = db.collection("Posts").document("post")
let document = try await docRef.getDocument()
let post = try document.data(as: Post.self)
return (image, post.description)
Firebase in a Widget

101. Architecture Swi!UI 2 Life Cycle
Firebase Firestore Authentication Combine async/await Completion block
WidgetKit

102. Authentication
Photo by Conve&Kit on Unsplash

103. Authentication
Photo by Eduardo Soares on Unsplash

104. Authentication
Photo by Victor Freitas on Unsplash

105. 

106. Sign in the user
Update the data model
Secure users’ data
How to implement
Firebase Authentication?

107. Anonymous Authentication
“Guest” accounts, rather

108. func signIn() {
registerStateListener()
if Auth.auth().currentUser !& nil {
Auth.auth().signInAnonymously()
}
}
Anonymous Authentication

110. 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

111. 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

112. 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

113. 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

114. 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

115. 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

116. All books are stored in one single collection
Which user do
they belong to?

117. let query = db.collection("books")
.whereField("userId",
isEqualTo: self.userId)
query
.addSnapshotListener { [weak self] (querySnapsho
guard let documents = querySnapshot!$documents els
Signed in user

118. 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

119. Architecture Swi!UI 2 Life Cycle
Firebase Firestore Authentication Combine async/await Completion block
WidgetKit

120. Combine

121. auth!$signInAnonymously()
let user = auth!$currentUser
print("User signed in with user ID: (user!$uid)")
This might be nil

122. 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

123. 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)")
}
@Published var user: User?
!!'
auth!$signInAnonymously()
.map{ $0.user }
.replaceError(with: nil)
.assign(to: &$user)
Even better

124. Launched with Firebase 8.9.0
h"ps://github.com/%rebase/%rebase-ios-sdk/projects/3

125. Architecture Swi!UI 2 Life Cycle
Firebase Firestore Authentication Combine async/await Completion block
WidgetKit

126. async/await
Photo by Stephen H on Unsplash

127. 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

128. 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

129. 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

130. 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

131. 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

132. 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

133. 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

134. Learn more
h"ps://pete#riese.dev/async-await-in-swi!
h"ps://www.youtube.com/watch?v=sEKw2BMcQtQ

135. Architecture Swi!UI 2 Life Cycle
Firebase Firestore Authentication Combine async/await Completion block
WidgetKit

136. Architecture Swi!UI 2 Life Cycle
Firebase Firestore Authentication Combine async/await Completion block
WidgetKit

137. Register now - it’s free!
h"ps://io.google/2022/
Google I/O 2022

138. Thanks! @pete#riese
h"ps://github.com/pete#riese/BookShelf
Code
@charlo"eCLiang

139. Credits
%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& 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&esy h"ps://%rebase.google.com/brand-guidelines
Firebase logos cou&esy h"ps://%rebase.google.com/brand-guidelines
Thanks!
Hea& by Roman from the Noun Project
Dashboard by BomSymbols from the Noun Project

140. The End.