Programming Cocoa with Ruby: Create Compelling Mac Apps Using RubyCocoa (The Facets of Ruby Series)

387 Pages·2009·5.47 MB·English

by  Brian Marick

What Readers Are Saying About
Programming Cocoa with Ruby
This isn’t just a book on RubyCocoa; it is probably the best book I’ve
seen that explains Cocoa technology. It actually explains how some of
the core technologies, especially bindings, work instead of just show-
ing an example of how to use them.
Allison Newman
Cocoa application developer
Learning a new API is hard enough, but learning a new API and a new
programming language at the same time can be overwhelming. Pro-
gramming Cocoawith Ruby is written for those of us used to a lan-
guage like Ruby or Python who want to learn about all the great stuff
Cocoa has to offer.
Jeremy McAnally
Developer, entp
The influence of Smalltalk on Ruby and Objective-C is considerable.
It shouldn’t be a surprise then that Cocoa, whose native tongue is
Objective-C, can be effectively learned and programmed from Ruby
in a way that captures the succinctness and expressiveness of this
newly popular scripting language. Brian’s book is a great introduc-
tion to the agile development of Cocoa apps, it serves as a primer on
Cocoa, and it demonstrates sound and thoughtful development prac-
tices and hygiene throughout.
Jerry Kuch
Principal engineer, EMC Corporation
Programming Cocoa with Ruby
Create Compelling Mac Apps Using RubyCocoa
Brian Marick
The Pragmatic Bookshelf
Raleigh,NorthCarolina Dallas,Texas
Many of the designations used by manufacturers and sellers to distinguish their prod-
uctsareclaimedastrademarks.Wherethosedesignationsappearinthisbook,andThe
Pragmatic Programmers, LLC was aware of a trademark claim, the designations have
been printed in initial capital letters or in all capitals. The Pragmatic Starter Kit, The
PragmaticProgrammer,PragmaticProgramming,PragmaticBookshelfandthelinkingg
devicearetrademarksofThePragmaticProgrammers,LLC.
Every precaution was taken in the preparation of this book. However, the publisher
assumesnoresponsibility for errorsor omissions,or for damagesthatmay result from
theuseofinformation(includingprogramlistings)containedherein.
Our Pragmatic courses, workshops, and other products can help you and your team
create better software and have more fun. For more information, as well as the latest
Pragmatictitles,pleasevisitusat
http://www.pragprog.com
Copyright©2009BrianMarick.
Allrightsreserved.
Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmit-
ted, in any form, or by any means, electronic,mechanical,photocopying, recording, or
otherwise,withoutthepriorconsentofthepublisher.
PrintedintheUnitedStatesofAmerica.
ISBN-10:1-934356-19-0
ISBN-13:978-1-934356-19-7
Printedonacid-freepaper.
P1.0printing,July2009
Version:2009-8-6
Contents
1 Introduction 11
1.1 What Is Cocoa? . . . . . . . . . . . . . . . . . . . . . . . 12
1.2 What Is RubyCocoa? . . . . . . . . . . . . . . . . . . . . 12
1.3 What’s It Like to Learn Cocoa Using Ruby? . . . . . . . 12
1.4 RubyCocoa? That’s So Last Year! . . . . . . . . . . . . . 13
1.5 Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.6 Versions . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.7 Our Example App . . . . . . . . . . . . . . . . . . . . . . 16
1.8 Centuries of the Bookmaker’s Art: Scorned . . . . . . . 18
1.9 Some Terminology . . . . . . . . . . . . . . . . . . . . . 19
1.10 Service After the Sale . . . . . . . . . . . . . . . . . . . . 19
1.11 Solving Problems . . . . . . . . . . . . . . . . . . . . . . 19
1.12 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 20
2 How Do We Get This Thing Started? 22
2.1 A Program That Prints . . . . . . . . . . . . . . . . . . . 23
2.2 Putting an Item in the Status Bar . . . . . . . . . . . . 26
2.3 Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.4 An Application Bundle . . . . . . . . . . . . . . . . . . . 31
2.5 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 35
I A First Realistic App 36
3 Working with Interface Builder and Xcode 37
3.1 The Basics . . . . . . . . . . . . . . . . . . . . . . . . . . 38
3.2 Creating and Editing Classes in Xcode . . . . . . . . . . 48
3.3 Debugging . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.4 SynchronizingInterface Builder and Xcode . . . . . . . 57
3.5 Attributes . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.6 Overriding Window Behavior with a Delegate . . . . . . 60
CONTENTS 6
3.7 Try This Yourself . . . . . . . . . . . . . . . . . . . . . . 61
3.8 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4 One Good App Observes Another 62
4.1 Notifications Within an App . . . . . . . . . . . . . . . . 62
4.2 Notifications Between Apps . . . . . . . . . . . . . . . . 67
4.3 The App to Fenestrate . . . . . . . . . . . . . . . . . . . 70
4.4 Putting Notification Handling Behind the GUI . . . . . 71
4.5 Reopening Objective-C Classes . . . . . . . . . . . . . . 73
4.6 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 73
II Reshaping Fenestra 75
5 A Better GUI 76
5.1 Toggle Buttons . . . . . . . . . . . . . . . . . . . . . . . 77
5.2 The Default Button . . . . . . . . . . . . . . . . . . . . . 78
5.3 Combo Box Items . . . . . . . . . . . . . . . . . . . . . . 79
5.4 The Initial First Responder . . . . . . . . . . . . . . . . 80
5.5 Try This Yourself . . . . . . . . . . . . . . . . . . . . . . 80
5.6 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6 Decoupled Controllers 82
6.1 Ignorant Objects . . . . . . . . . . . . . . . . . . . . . . 83
6.2 Extracting Subclasses . . . . . . . . . . . . . . . . . . . 85
6.3 Reacting to Button State . . . . . . . . . . . . . . . . . . 90
6.4 Using Nibs to Avoid Dependencies . . . . . . . . . . . . 90
6.5 Initializing Combo Boxes . . . . . . . . . . . . . . . . . . 92
6.6 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 93
7 Notifications Connect Decoupled Objects 94
7.1 Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . 94
7.2 Translators and the Rising Tide of Ugliness . . . . . . . 96
7.3 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 99
8 More Expressive Code 100
8.1 A DSL for Notifications . . . . . . . . . . . . . . . . . . . 101
8.2 RubyCocoa Has Two Ways of Referringto Superclasses 103
8.3 Shorthand for Posting Notifications . . . . . . . . . . . 103
8.4 Try This Yourself . . . . . . . . . . . . . . . . . . . . . . 105
8.5 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Reporterratum
thiscopyis(P1.0printing,July2009)
CONTENTS 7
III Project Mechanics 108
9 Bundling Gems and Libraries with Your App 109
9.1 Manual Control . . . . . . . . . . . . . . . . . . . . . . . 110
9.2 Standaloneify . . . . . . . . . . . . . . . . . . . . . . . . 114
9.3 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 116
10 Project Organization, Builds, and Your Favorite Editor 117
10.1 Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
10.2 Using Xcode with Hierarchical Project Folders . . . . . 119
10.3 Running in Place . . . . . . . . . . . . . . . . . . . . . . 121
10.4 Building Without Xcode . . . . . . . . . . . . . . . . . . 121
10.5 Using InterfaceBuilder with Hierarchical Project Folders123
10.6 Startinga New Project . . . . . . . . . . . . . . . . . . . 124
10.7 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 125
IV Declarative Data Handling 126
11 Persistent User Preferences 127
11.1 The User PreferencesSystem . . . . . . . . . . . . . . . 128
11.2 Storing Custom Objects as Preferences . . . . . . . . . 131
11.3 Using Archived Objects. . . . . . . . . . . . . . . . . . . 139
11.4 Views Can Pull Data . . . . . . . . . . . . . . . . . . . . 143
11.5 Try This Yourself: A Sticky Window . . . . . . . . . . . 145
11.6 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 149
12 Creating a Preference Panel in a New Nib 150
12.1 Creating a Nib . . . . . . . . . . . . . . . . . . . . . . . . 151
12.2 Drawing the Panel . . . . . . . . . . . . . . . . . . . . . 153
12.3 Hooking the Panel to the App . . . . . . . . . . . . . . . 155
12.4 The Nib File’s Owner . . . . . . . . . . . . . . . . . . . . 158
12.5 IB’s First Responder Pseudo-Object . . . . . . . . . . . 159
12.6 Memory Leaks . . . . . . . . . . . . . . . . . . . . . . . . 160
12.7 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 161
13 Implementing a Preference Panel with Cocoa Bindings 162
13.1 Binding a Simple Value . . . . . . . . . . . . . . . . . . 162
13.2 Binding an Array of Hashes . . . . . . . . . . . . . . . . 166
13.3 Formatters . . . . . . . . . . . . . . . . . . . . . . . . . . 172
13.4 Value Transformers . . . . . . . . . . . . . . . . . . . . . 177
Reporterratum
thiscopyis(P1.0printing,July2009)
CONTENTS 8
13.5 Adding and Deleting Table Rows . . . . . . . . . . . . . 182
13.6 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 184
14 Setting Up Bindings with Code 185
14.1 Oh No! Terminology! . . . . . . . . . . . . . . . . . . . . 185
14.2 Using Rooted Keypaths in Code . . . . . . . . . . . . . . 189
14.3 Subclassing NSArrayController . . . . . . . . . . . . . . 189
14.4 bind_toObject_withKeyPath_options . . . . . . . . . . . 192
14.5 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 196
V Fun with Tables 197
15 Prologue: Folders and Tests 198
15.1 Disk Layout . . . . . . . . . . . . . . . . . . . . . . . . . 198
16 Selections and Editing 202
16.1 An Example of Creating Tests: The Add Method . . . . 202
16.2 Working with an Uncooperative Control . . . . . . . . . 212
16.3 Try This Yourself . . . . . . . . . . . . . . . . . . . . . . 220
16.4 Building Setup Methods . . . . . . . . . . . . . . . . . . 227
16.5 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 229
17 Buttons in Tables 230
17.1 Cells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
17.2 Making the Change . . . . . . . . . . . . . . . . . . . . . 231
17.3 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 233
18 A Formatter with Two Wrinkles 234
18.1 The Formatter Code . . . . . . . . . . . . . . . . . . . . 235
18.2 Calling Methods That Take Reference Arguments . . . 237
18.3 Breaking Encapsulation in Tests . . . . . . . . . . . . . 240
18.4 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 242
19 Picking Files with Open Panels 243
19.1 NSOpenPanel . . . . . . . . . . . . . . . . . . . . . . . . 243
19.2 A Design for Using NSOpenPanel in Fenestra . . . . . . 246
19.3 Try This Yourself: PreferencesController Tests . . . . . 248
19.4 Try This Yourself: The NSOpenPanel Controller . . . . 256
19.5 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 258
Reporterratum
thiscopyis(P1.0printing,July2009)
CONTENTS 9
20 Drag and Drop 261
20.1 How Drag and Drop Works . . . . . . . . . . . . . . . . 261
20.2 Designing the GUI . . . . . . . . . . . . . . . . . . . . . 263
20.3 A Template for the Solution . . . . . . . . . . . . . . . . 264
20.4 Utility Classes and Modules . . . . . . . . . . . . . . . . 265
20.5 Try This Yourself: Lively Dragging Info . . . . . . . . . . 268
20.6 Try This Yourself: Drag and Drop . . . . . . . . . . . . . 275
20.7 Does It Work? . . . . . . . . . . . . . . . . . . . . . . . . 280
20.8 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 281
21 Epilogue: A Wonderful World of Tests 282
21.1 Test-Driven Design . . . . . . . . . . . . . . . . . . . . . 282
21.2 To Learn More . . . . . . . . . . . . . . . . . . . . . . . . 285
VI Wrapping Up 286
22 Fit and Finish 287
22.1 Saving the Window Position Until the Next Launch . . 287
22.2 Tab Behavior. . . . . . . . . . . . . . . . . . . . . . . . . 288
22.3 Using NSMatrix to Organize Buttons . . . . . . . . . . . 289
22.4 Sizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293
22.5 Cleaning Up the Menu Bar . . . . . . . . . . . . . . . . 297
22.6 The About Window . . . . . . . . . . . . . . . . . . . . . 297
22.7 Changing the Application’s Name . . . . . . . . . . . . . 299
23 Adding Help 301
23.1 Help Book Basics . . . . . . . . . . . . . . . . . . . . . . 301
23.2 Creating a Help Book . . . . . . . . . . . . . . . . . . . . 302
23.3 Editing Pages . . . . . . . . . . . . . . . . . . . . . . . . 303
23.4 Hooking a Help Book into an App. . . . . . . . . . . . . 309
23.5 A Workflow for Creating Help Book Pages . . . . . . . . 311
23.6 Tooltips . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
24 Document-Based Applications 313
24.1 The Major Players . . . . . . . . . . . . . . . . . . . . . . 314
24.2 The Responder Chain. . . . . . . . . . . . . . . . . . . . 316
24.3 Creating a New Document . . . . . . . . . . . . . . . . . 319
24.4 Opening and Saving Documents . . . . . . . . . . . . . 328
24.5 Editing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 330
24.6 Learning More . . . . . . . . . . . . . . . . . . . . . . . . 333
Reporterratum
thiscopyis(P1.0printing,July2009)
CONTENTS 10
25 MacRuby 334
25.1 Getting MacRuby . . . . . . . . . . . . . . . . . . . . . . 337
25.2 MacRuby Basics . . . . . . . . . . . . . . . . . . . . . . . 337
25.3 A MacRuby Checklist . . . . . . . . . . . . . . . . . . . . 339
25.4 What Now? . . . . . . . . . . . . . . . . . . . . . . . . . . 343
VII Reference 344
26 The Objective-C Bridge and Bridge Metadata 345
26.1 An Unexpected Return Value . . . . . . . . . . . . . . . 345
26.2 What Information Can Be Found at Runtime? . . . . . 346
26.3 Supplementing Runtime Information . . . . . . . . . . 347
26.4 Our Own Private Metadata. . . . . . . . . . . . . . . . . 348
26.5 Finding Out More . . . . . . . . . . . . . . . . . . . . . . 349
27 The Underpinnings of Cocoa Bindings 350
27.1 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 350
27.2 Our Goal . . . . . . . . . . . . . . . . . . . . . . . . . . . 351
27.3 Declaring Observed Properties . . . . . . . . . . . . . . 352
27.4 Observing Changes . . . . . . . . . . . . . . . . . . . . . 353
27.5 Implementing bind_toObject_withKeyPath_options . . 355
27.6 Changing the Value of an Observed Key . . . . . . . . . 356
27.7 In Summary... . . . . . . . . . . . . . . . . . . . . . . . . 357
27.8 Postscript: Observing Changes to Collections . . . . . . 359
A Glossary 361
B Bibliography 372
Index 376
Reporterratum
thiscopyis(P1.0printing,July2009)