Programming Cocoa with Ruby

387 Pages·2009·11.417 MB·English

by  Brian Marick

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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
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Programming Cocoa with Ruby
Create Compelling Mac Apps Using RubyCocoa
Brian Marick
The Pragmatic Bookshelf
Raleigh,NorthCarolina Dallas,Texas
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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
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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
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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
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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
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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
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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
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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
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