RxSwift. Reactive Programming with Swift

398 Pages·2017·24.54 MB·English

by  Florent Pillet

RxSwift - Reactive Programming with Swift
RxSwift: Reactive Programming with Swift
Florent Pillet, Junior Bontognali, Marin Todorov & Scott Gardner
Copyright ©2017 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.
Notice of Liability
This book and all corresponding materials (such as source code) are provided on an
“as is” basis, without warranty of any kind, express of implied, including but not
limited to the warranties of merchantability, fitness for a particular purpose, and
noninfringement. In no event shall the authors or copyright holders be liable for any
claim, damages or other liability, whether in action of contract, tort or otherwise,
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.
raywenderlich.com 2
RxSwift - Reactive Programming with Swift
Dedications
"For my father."
— Marin Todorov
"For Fabienne and Alexandra"
— Florent Pillet
"For my grandfather."
— Junior Bontognali
"For Betty ! "
— Scott Gardner
raywenderlich.com 3
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.
Junior Bontognali is an author of this book. Junior has been
developing on iOS since the first iPhone and joined the RxSwift
team in the early development stage. Based in Switzerland, when
he's not eating cheese or chocolate, he's doing some cool stuff in
the mobile space, without denying to work on other technologies.
Other than that he organizes tech events, speaks and blogs. Say
hello to Junior on Twitter at @bontoJR.
Marin Todorov is an author of this book. Marin is one of the
founding members of the raywenderlich.com team and has worked
on seven 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 has been
developing iOS apps since 2010, Swift since the day it was
announced, and RxSwift since before version 1. He's authored
several video courses, tutorials, and articles on iOS app
development, presented at numerous conferences, meetups, and
online events, and this is his second book. Say hello to Scott on
Twitter at @scotteg.
raywenderlich.com 4
RxSwift - Reactive Programming with Swift
About the editors
Ash Furrow is the technical editor of this book. Ash is a Canadian
iOS developer and author, currently working at Artsy. He has
published a number of books, built many apps, and is a
contributor to the open source community. On his blog
ashfurrow.com, he writes about a range of topics, from interesting
programming to explorations of analogue film photography.
Chris Belanger is the editor of this book. Chris Belanger is the
Book Team Lead and Lead Editor for raywenderlich.com. If there
are words to wrangle or a paragraph to ponder, he‘s on the case.
When he kicks back, you can usually find Chris with guitar in hand,
looking for the nearest beach, or exploring the lakes and rivers in
his part of the world in a canoe.
Marin Todorov is the final pass editor of this book. Marin is one
of the founding members of the raywenderlich.com team and has
worked on seven of the team's books. Besides crafting code, Marin
also enjoys blogging, teaching, and speaking at conferences. He
happily open-sources code.
raywenderlich.com 5
RxSwift - Reactive Programming with Swift
Table of Contents: Overview
Introduction................................................................................ 15
Section I: Getting Started with RxSwift ........................ 21
Chapter 1: Hello RxSwift!.............................................. 22
Chapter 2: Observables................................................ 43
Chapter 3: Subjects......................................................... 62
Chapter 4: Observables and Subjects in Practice.... 76
Section II: Operators and Best Practices....................... 95
Chapter 5: Filtering Operators..................................... 96
Chapter 6: Filtering Operators in Practice .............. 114
Chapter 7: Transforming Operators ......................... 134
Chapter 8: Transforming Operators in Practice...... 146
Chapter 9: Combining Operators ............................. 168
Chapter 10: Combining Operators in Practice....... 188
Chapter 11: Time Based Operators ......................... 208
Section III: iOS Apps with RxCocoa........................... 227
Chapter 12: Beginning RxCocoa ............................... 228
Chapter 13: Intermediate RxCocoa.......................... 247
Section IV: Intermediate RxSwift/RxCocoa................ 267
Chapter 14: Error Handling in Practice.................... 268
Chapter 15: Intro To Schedulers ................................ 285
Chapter 16: Testing with RxTest................................. 299
raywenderlich.com 6
RxSwift - Reactive Programming with Swift
Chapter 17: Creating Custom Reactive Extensions. 314
Section V: RxSwift Community Cookbook................. 329
Chapter 18: Table and Collection Views ................. 330
Chapter 19: Action....................................................... 334
Chapter 20: RxGesture ............................................... 339
Chapter 21: RxRealm................................................... 343
Chapter 22: RxAlamofire............................................ 348
Section VI: Putting it All Together .............................. 352
Chapter 23: MVVM with RxSwift .............................. 353
Chapter 24: Building a Complete RxSwift App...... 375
Conclusion ............................................................................... 398
raywenderlich.com 7
RxSwift - Reactive Programming with Swift
Table of Contents: Extended
Introduction................................................................................ 15
What you need.................................................................................................................. 16
Who this book is for.......................................................................................................... 16
How to use this book......................................................................................................... 17
What’s in store................................................................................................................... 17
Book source code and forums......................................................................................... 18
Book updates...................................................................................................................... 18
License.................................................................................................................................. 19
About the cover.................................................................................................................. 20
Section I: Getting Started with RxSwift ........................ 21
Chapter 1: Hello RxSwift! ...................................................... 22
Introduction to asynchronous programming.................................................................. 23
Foundation of RxSwift....................................................................................................... 30
App architecture................................................................................................................ 37
RxCocoa.............................................................................................................................. 38
Installing RxSwift................................................................................................................ 39
Community........................................................................................................................... 41
Where to go from here?.................................................................................................. 42
Chapter 2: Observables........................................................ 43
Getting started.................................................................................................................. 44
What is an observable?................................................................................................... 45
Lifecycle of an observable.............................................................................................. 46
Creating observables....................................................................................................... 47
Subscribing to observables.............................................................................................. 49
Disposing and terminating............................................................................................... 54
Creating observable factories........................................................................................ 59
Challenges........................................................................................................................... 60
raywenderlich.com 8
RxSwift - Reactive Programming with Swift
Chapter 3: Subjects................................................................. 62
Getting started.................................................................................................................. 63
What are subjects?............................................................................................................ 64
Working with PublishSubjects.......................................................................................... 64
Working with BehaviorSubjects....................................................................................... 67
Working with ReplaySubjects.......................................................................................... 69
Working with Variables.................................................................................................... 72
Challenges........................................................................................................................... 74
Chapter 4: Observables and Subjects in Practice ............ 76
Getting started.................................................................................................................. 77
Using a variable in a view controller............................................................................. 78
Talking to other view controllers via subjects............................................................... 81
Which dispose bag to use?.............................................................................................. 86
Creating a custom observable........................................................................................ 89
Challenges........................................................................................................................... 94
Section II: Operators and Best Practices....................... 95
Chapter 5: Filtering Operators............................................. 96
Getting started.................................................................................................................. 97
Ignoring operators............................................................................................................. 97
Skipping operators......................................................................................................... 101
Taking operators............................................................................................................. 105
Distinct operators ............................................................................................................ 109
Challenges........................................................................................................................ 111
Chapter 6: Filtering Operators in Practice ...................... 114
Improving the Combinestagram project...................................................................... 115
Sharing subscriptions...................................................................................................... 116
Improving the photo selector......................................................................................... 123
Trying out time based filter operators........................................................................ 130
Challenges........................................................................................................................ 133
raywenderlich.com 9
RxSwift - Reactive Programming with Swift
Chapter 7: Transforming Operators.................................. 134
Getting started................................................................................................................ 135
Transforming elements.................................................................................................... 135
Transforming inner observables................................................................................... 138
Challenges........................................................................................................................ 143
Chapter 8: Transforming Operators in Practice.............. 146
Getting started with GitFeed....................................................................................... 147
Fetching data from the web.......................................................................................... 148
Transforming the response............................................................................................. 152
Intermission: Handling erroneous input........................................................................ 157
Persisting objects to disk................................................................................................ 158
Add a Last-Modified header to the request............................................................. 159
Challenges........................................................................................................................ 163
Chapter 9: Combining Operators...................................... 168
Getting started................................................................................................................ 169
Prefixing and concatenating......................................................................................... 169
Merging............................................................................................................................. 172
Combining elements........................................................................................................ 174
Triggers............................................................................................................................. 179
Switches............................................................................................................................. 181
Combining elements within a sequence....................................................................... 184
Challenges........................................................................................................................ 187
Chapter 10: Combining Operators in Practice ............... 188
Getting started................................................................................................................ 189
Preparing the web backend service........................................................................... 189
Categories view controller............................................................................................ 193
Adding the event download service............................................................................ 194
Getting events for categories....................................................................................... 196
Events view controller..................................................................................................... 200
Wiring the days selector............................................................................................... 202
Splitting event downloads............................................................................................. 204
Challenges........................................................................................................................ 207
raywenderlich.com 10