Core Data by Tutorials: iOS 12 and Swift 4.2 Edition

278 Pages·2018·40.609 MB·English

by  Raywenderlich.com Team, Aaron Douglas, Saul Mora, Matthew Morey, Pietro Rea

Core Data by Tutorials
Core Data by Tutorials Fifth Edition
Aaron Douglas, Matthew Morey and Pietro Rea
Copyright ©2018 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.
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Core Data by Tutorials
Dedications
"To my husband, Mike, who puts up with all my weird quirks and
supports all the things I do."
— Aaron Douglas
"To my amazing wife Tricia and my parents — Thanks for always
supporting me."
— Matthew Morey
"To my wonderful wife Emily, my daughter Rose, and my parents.
Thank you for always supporting me every step of the way."
— Pietro Rea
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About the Authors
Aaron Douglas was that kid taking apart the mechanical and
electrical appliances at five years of age to see how they worked. He
never grew out of that core interest — to know how things work. He
took an early interest in computer programming, figuring out how to
get past security to be able to play games on his dad's computer. He's
still that feisty nerd, but at least now he gets paid to do it. Aaron's
interest in mobile software has been ever increasing since he got his
first iOS app in Apple's App Store in 2009, Migraine Diary. He is with
Automattic (WordPress.com, Akismet, SimpleNote) as a Mobile
Maker. Other than software development, Aaron enjoys camping
during the summer, taking his dogs for a walk around the
neighborhood, and pretending to be a storm chaser while sitting at
home. Follow him on Twitter as @astralbodies and on his blog
at https://aaron.blog.
Matthew Morey is an engineer, author, hacker, creator and tinkerer.
As an active member of the iOS community and CTO at MJD
Interactive he has led numerous successful mobile projects
worldwide. When not developing apps he enjoys traveling,
snowboarding, and surfing. He blogs about technology and business
at matthewmorey.com.
Pietro Rea is a senior software engineer at Upside Travel in
Washington D.C. Pietro's work has been featured in the App Store
across several categories: media, e-commerce, lifestyle and more.
Having worked at Fortune 500 companies and venture-backed
startups, Pietro has a passion for building apps users can't live
without. You can find Pietro on Twitter as @pietrorea.
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Core Data by Tutorials
About the Editors
Darren Ferguson is the technical editor for this book. He is an
experienced software developer and works for M.C. Dean, Inc, a
systems integration provider from North Virginia. When he's not
coding, you'll find him enjoying EPL Football, traveling as much as
possible and spending time with his wife and daughter. Find Darren
on Twitter as @darren102.
Chris Belanger is the editor of this book. Chris is the Editor-in-Chief
for raywenderlich.com. He was a developer for nearly 20 years in
various fields from e-health to aerial surveillance to industrial
controls. 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. Twitter: @crispytwit.
Rich Turton is the final pass editor of this book. Rich is an iOS
developer for MartianCraft and long-time contributor
to raywenderlich.com. When he's not in front of a computer he is
usually trying to play the piano, trying to make fancy cocktails, or
trying to play elaborate Lego games with his daughters. Sometimes
all at the same time.
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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Core Data by Tutorials
Table of Contents: Overview
Introduction ............................................................................. 11
Chapter 1: Your First Core Data App............................. 17
Chapter 2: NSManagedObject Subclasses .................. 38
Chapter 3: The Core Data Stack ...................................... 66
Chapter 4: Intermediate Fetching................................... 89
Chapter 5: NSFetchedResultsController................... 123
Chapter 6: Versioning & Migration .............................. 149
Chapter 7: Unit Testing ..................................................... 188
Chapter 8: Measuring & Boosting Performance..... 206
Chapter 9: Multiple Managed Object Contexts...... 239
Conclusion.............................................................................. 259
More Books You Might Enjoy ......................................... 260
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Table of Contents: Extended
Introduction ............................................................................. 11
What you need.................................................................................................................... 12
Who this book is for.......................................................................................................... 13
How to use this book........................................................................................................ 13
What’s in store.................................................................................................................... 13
Source code and forums.................................................................................................. 14
Updates.................................................................................................................................. 15
License.................................................................................................................................... 15
About the cover.................................................................................................................. 16
Chapter 1: Your First Core Data App............................. 17
Getting started................................................................................................................... 18
Modeling your data........................................................................................................... 27
Saving to Core Data.......................................................................................................... 30
Fetching from Core Data................................................................................................ 34
Key points............................................................................................................................. 37
Chapter 2: NSManagedObject Subclasses .................. 38
Getting started................................................................................................................... 38
Modeling your data........................................................................................................... 41
Storing non-standard data types in Core Data...................................................... 45
Managed object subclasses........................................................................................... 46
Propagating a managed context.................................................................................. 51
Data validation in Core Data......................................................................................... 60
Tying everything up........................................................................................................... 63
Key points............................................................................................................................. 65
Chapter 3: The Core Data Stack ...................................... 66
Getting started................................................................................................................... 66
Rolling your own Core Data stack............................................................................... 67
The managed object model............................................................................................ 68
The persistent store.......................................................................................................... 68
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The persistent store coordinator................................................................................ 69
The managed object context......................................................................................... 70
The persistent store container..................................................................................... 71
Creating your stack object............................................................................................. 71
Modeling your data........................................................................................................... 74
Adding managed object subclasses............................................................................ 78
A walk down persistence lane...................................................................................... 81
Deleting objects from Core Data................................................................................ 85
Key points............................................................................................................................. 88
Chapter 4: Intermediate Fetching................................... 89
NSFetchRequest: the star of the show...................................................................... 89
Introducing the Bubble Tea app................................................................................... 91
Stored fetch requests....................................................................................................... 94
Fetching different result types..................................................................................... 98
Sorting fetched results.................................................................................................. 114
Asynchronous fetching................................................................................................. 117
Batch updates: no fetching required....................................................................... 119
Key Points.......................................................................................................................... 121
Chapter 5: NSFetchedResultsController................... 123
Introducing the World Cup app................................................................................. 124
It all begins with a fetch request............................................................................... 126
Grouping results into sections................................................................................... 133
“Cache” the ball................................................................................................................ 136
Monitoring changes....................................................................................................... 137
Inserting an underdog................................................................................................... 143
Key Points.......................................................................................................................... 147
Where to go from here?................................................................................................ 148
Chapter 6: Versioning & Migration .............................. 149
When to migrate.............................................................................................................. 149
The migration process................................................................................................... 150
Types of migrations........................................................................................................ 151
Getting started................................................................................................................. 152
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A lightweight migration................................................................................................ 153
Inferred mapping models............................................................................................. 155
A manual migration........................................................................................................ 160
A complex mapping model........................................................................................... 169
Migrating non-sequential versions.......................................................................... 176
A self-migrating stack.................................................................................................... 176
Testing sequential migrations.................................................................................... 186
Key points........................................................................................................................... 187
Chapter 7: Unit Testing ..................................................... 188
Getting started................................................................................................................. 189
Core Data stack for testing......................................................................................... 190
Asynchronous tests........................................................................................................ 196
Tests first............................................................................................................................ 198
Validation and refactoring........................................................................................... 202
Key points........................................................................................................................... 205
Where to go from here?................................................................................................ 205
Chapter 8: Measuring & Boosting Performance..... 206
Getting started................................................................................................................. 206
Measure, change, verify................................................................................................ 208
Fetching and performance.......................................................................................... 219
Key points........................................................................................................................... 237
Challenge............................................................................................................................ 238
Chapter 9: Multiple Managed Object Contexts...... 239
Getting started................................................................................................................. 240
Introducing SurfJournal............................................................................................... 240
Doing work in the background.................................................................................. 244
Editing on a scratchpad................................................................................................. 251
Key points........................................................................................................................... 257
Challenge............................................................................................................................ 258
Conclusion.............................................................................. 259
More Books You Might Enjoy ......................................... 260
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New to iOS or Swift?...................................................................................................... 260
Experienced iOS developer?....................................................................................... 262
Want to make games?.................................................................................................... 273
Want to learn Android or Kotlin?.............................................................................. 277
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