RxSwift: Reactive Programming with Swift (Fourth Edition)

472 Pages·2021·28.534 MB·English

by  Junior Bontognali, Scott Gardner, Florent Pillet, Shai Mishali, Marin Todorov

RxSwift - Reactive Programming with Swift
RxSwift: Reactive Programming with Swift
By Junior Bontognali, Scott Gardner, Shai Mishali, Florent Pillet & Marin Todorov
Copyright ©2020 Razeware LLC.
Notice of Rights
All rights reserved. No part of this book or corresponding materials (such as text,
images, or source code) may be reproduced or distributed by any means without prior
written permission of the copyright owner.
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noninfringement. In no event shall the authors or copyright holders be liable for any
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arising from, out of or in connection with the software or the use of other dealing in
the software.
Trademarks
All trademarks and registered trademarks appearing in this book are the property of
their own respective owners.
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RxSwift - Reactive Programming with Swift
Dedications
"To my father. To my mom. To Mirjam and our beautiful
daughter."
— Marin Todorov
"For Fabienne, Alexandra, and all the rabbits."
— Florent Pillet
"For Elia and Baby Ethan. To my father and mother."
— Shai Mishali
"For Charlotte"
— Scott Gardner
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RxSwift - Reactive Programming with Swift
About the Authors
Florent Pillet is an author of this book. Florent has been
developing for mobile platforms since the last century and moved
to iOS on day 1. He adopted reactive programming before Swift was
announced and has been using RxSwift in production since 2015. A
freelance developer, Florent also uses Rx on Android and likes
working on tools for developers like the popular NSLogger when
he's not contracting for clients worldwide. Say hello to Florent on
Twitter at @fpillet.
Shai Mishali is an author and the final pass editor on this book.
He's the iOS Tech Lead for Gett, the global on-demand mobility
company; as well as an international speaker, a multi-book author
and editor, and a highly active open-source contributor and
maintainer on several high-profile projects - namely, the RxSwift
Community and RxSwift projects, but also releases many open-
source endeavors around Combine such as CombineCocoa,
RxCombine and more. As an avid enthusiast of hackathons, Shai
took 1st place at BattleHack Tel-Aviv 2014, BattleHack World Finals
San Jose 2014, and Ford's Developer Challenge Tel-Aviv 2015. You
can find him on GitHub and Twitter as @freak4pc.
Marin Todorov is an author of this book. Marin is one of the
founding members of the raywenderlich.com team and has worked
on eight of the team's books. Besides crafting code, Marin also
enjoys blogging, teaching, and speaking at conferences. He happily
open-sources code. You can find out more about Marin at
www.underplot.com.
Scott Gardner is an author of this book. Scott is a veteran iOS app
architect and developer with over ten years of experience. He's
authored several books, video courses, tutorials, and articles on
Swift, RxSwift, and iOS app development. Additionally, Scott is an
Apple Certified Trainer for Swift and iOS, and he also enjoys
speaking at conferences, meetups, and online events. Say hello to
Scott on Twitter at @scotteg.
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RxSwift - Reactive Programming with Swift
About the Artist
Vicki Wenderlich is the designer and artist of the cover of this
book. She is Ray’s wife and business partner. She is a digital artist
who creates illustrations, game art and a lot of other art or design
work for the tutorials and books on raywenderlich.com. When she’s
not making art, she loves hiking, a good glass of wine and
attempting to create the perfect cheese plate.
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RxSwift - Reactive Programming with Swift
Table of Contents: Overview
Acknowledgements............................................................................... 16
Introduction.............................................................................................. 17
Book Updates........................................................................................... 21
Book License............................................................................................. 22
What You Need........................................................................................ 23
Section I: Getting Started with RxSwift...................... 24
Chapter 1: Hello, RxSwift!...................................................... 25
Chapter 2: Observables........................................................... 48
Chapter 3: Subjects.................................................................... 72
Chapter 4: Observables & Subjects in Practice.............. 90
Section II: Operators & Best Practices...................... 112
Chapter 5: Filtering Operators........................................... 114
Chapter 6: Filtering Operators in Practice.................... 134
Chapter 7: Transforming Operators................................. 157
Chapter 8: Transforming Operators in Practice.......... 174
Chapter 9: Combining Operators...................................... 195
Chapter 10: Combining Operators in Practice............ 217
Chapter 11: Time-Based Operators................................. 240
Section III: iOS Apps with RxCocoa........................... 261
Chapter 12: Beginning RxCocoa........................................ 262
Chapter 13: Intermediate RxCocoa................................. 285
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Section IV: Intermediate RxSwift/RxCocoa ........... 310
Chapter 14: Error Handling in Practice.......................... 311
Chapter 15: Intro to Schedulers........................................ 332
Chapter 16: Testing with RxTest........................................ 348
Chapter 17: Creating Custom Reactive Extensions.. 365
Section V: RxSwift Community Cookbook.............. 383
Chapter 18: Table & Collection Views............................. 384
Chapter 19: RxSwiftExt......................................................... 389
Chapter 20: Action.................................................................. 394
Chapter 21: RxGesture.......................................................... 399
Chapter 22: Debugging with RxTimelane...................... 404
Chapter 23: RxAlamofire...................................................... 411
Section VI: Putting It All Together ............................. 416
Chapter 24: MVVM with RxSwift...................................... 417
Chapter 25: Building a Complete RxSwift App............ 442
Conclusion.............................................................................................. 471
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RxSwift - Reactive Programming with Swift
Table of Contents: Extended
Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Who this book is for. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
How to use this book. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
What’s in store. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Book Updates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Book License. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
What You Need . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Section I: Getting Started with RxSwift . . . . . . . . . . . . 24
Chapter 1: Hello, RxSwift! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Introduction to asynchronous programming. . . . . . . . . . . . . . . . . . . . . . . . . 26
Foundation of RxSwift. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
App architecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
RxCocoa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Installing RxSwift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
RxSwift and Combine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Community . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Where to go from here?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Chapter 2: Observables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
What is an observable? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Lifecycle of an observable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Creating observables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Subscribing to observables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Disposing and terminating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Creating observable factories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
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Using Traits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Chapter 3: Subjects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
What are subjects?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Working with publish subjects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Working with behavior subjects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Working with replay subjects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Working with relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Chapter 4: Observables & Subjects in Practice. . . . . . . . . . . . . . 90
Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Using a subject/relay in a view controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Talking to other view controllers via subjects . . . . . . . . . . . . . . . . . . . . . . . . 97
Creating a custom observable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
RxSwift traits in practice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Completable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Challenges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Section II: Operators & Best Practices. . . . . . . . . . . . 112
Chapter 5: Filtering Operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Getting started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Ignoring operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Skipping operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Taking operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Distinct operators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Challenge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Chapter 6: Filtering Operators in Practice . . . . . . . . . . . . . . . . . 134
Improving the Combinestagram project . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Sharing subscriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
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Improving the photo selector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Trying out time-based filter operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Challenge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Chapter 7: Transforming Operators. . . . . . . . . . . . . . . . . . . . . . . . 157
Getting started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Transforming elements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
Transforming inner observables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Observing events. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Challenge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Chapter 8: Transforming Operators in Practice. . . . . . . . . . . . 174
Getting started with GitFeed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Fetching data from the web . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
Transforming the response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Persisting objects to disk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Add a last-modified header to the request. . . . . . . . . . . . . . . . . . . . . . . . . . 187
Challenge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Chapter 9: Combining Operators . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Getting started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
Prefixing and concatenating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Merging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
Combining elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
Triggers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208
Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
Combining elements within a sequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Challenge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
Chapter 10: Combining Operators in Practice . . . . . . . . . . . . . 217
Getting started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Preparing the web backend service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
Categories view controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
Adding the event download service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
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