Objective-C Phrasebook

David Chisnall is an active contributor to the GNUstep project, which provides an open source implementation of the Cocoa APIs, and cofounded the Étoilé project. He has created a new Objective-C runtime library, worked on Objective-C support in the clang compiler, and published papers on Objective-C.

Introduction xiv

1 The Objective-C Philosophy 1

Understanding the Object Model 2

A Tale of Two Type Systems 4

C Is Objective-C 5

The Language and the Library 7

The History of Objective-C 9

Cross-Platform Support 13

Compiling Objective-C Programs 15

2 An Objective-C Primer 19

Declaring Objective-C Types 20

Sending Messages 24

Understanding Selectors 28

Declaring Classes 31

Using Protocols 36

Adding Methods to a Class 38

Using Informal Protocols 42

Synthesizing Methods with

Declared Properties 43

Understanding self, _cmd, super 49

Understanding the isa Pointer 52

Initializing Classes 55

Reading Type Encodings 58

Using Blocks 60

3 Memory Management 63

Retaining and Releasing 64

Assigning to Instance Variables 66

Automatic Reference Counting 67

Returning Objects via Pointer Arguments 70

Avoiding Retain Cycles 73

Migrating to ARC 75

Autorelease Pools 78

Using Autoreleased Constructors 81

Autoreleasing Objects in Accessors 82

Supporting Automatic Garbage Collection 83

Interoperating with C 85

Understanding Object Destruction 88

Using Weak References 90

Allocating Scanned Memory 93

4 Common Objective-C Patterns 95

Supporting Two-Stage Creation 96

Copying Objects 98

Archiving Objects 100

Creating Designated Initalizers 104

Enforcing the Singleton Pattern 107

Delegation 109

Providing Façades 111

Creating Class Clusters 113

Using Run Loops 116

5 Numbers 119

Storing Numbers in Collections 121

Performing Decimal Arithmetic 125

Converting Between Strings and Numbers 128

Reading Numbers from Strings 130

6 Manipulating Strings 133

Creating Constant Strings 134

Comparing Strings 135

Processing a String One Character at a Time 139

Converting String Encodings 142

Trimming Strings 145

Splitting Strings 146

Copying Strings 148

Creating Strings from Templates 150

Matching Patterns in Strings 154

Storing Rich Text 156

7 Working with Collections 159

Using Arrays 161

Manipulating Indexes 163

Storing Unordered Groups of Objects 165

Creating a Dictionary 167

Iterating Over a Collection 169

Finding an Object in a Collection 173

Subclassing Collections 176

Storing Objects in C++ Collections 179

8 Dates and Times 183

Finding the Current Date 184

Converting Dates for Display 186

Calculating Elapsed Time 189

Parsing Dates from Strings 191

Receiving Timer Events 192

9 Working with Property Lists 195

Storing Collections in Property Lists 196

Reading Data from

Property Lists 199

Converting Property List Formats 202

Using JSON 204

Storing User Defaults 206

Storing Arbitrary Objects in User Defaults 210

10 Interacting with the Environment 213

Getting Environment Variables 214

Parsing Command-Line Arguments 216

Accessing the User’s Locale 218

Supporting Sudden Termination 219

11 Key-Value Coding 223

Accessing Values by Key 224

Ensuring KVC Compliance 225

Understanding Key Paths 229

Observing Keys 231

Ensuring KVO Compliance 233

12 Handling Errors 237

Runtime Differences for Exceptions 238

Throwing and Catching Exceptions 242

Using Exception Objects 244

Using the Unified Exception Model 246

Managing Memory with Exceptions 247

Passing Error Delegates 250

Returning Error Values 252

Using NSError 253

13 Accessing Directories and Files 255

Reading a File 256

Moving and Copying Files 258

Getting File Attributes 260

Manipulating Paths 262

Determining if a File or Directory Exists 264

Working with Bundles 266

Finding Files in System Locations 269

14 Threads 273

Creating Threads 274

Controlling Thread Priority 275

Synchronizing Threads 278

Storing Thread-Specific Data 280

Waiting for a Condition 283

15 Blocks and Grand Central 287

Binding Variables to Blocks 288

Managing Memory with Blocks 293

Performing Actions in the Background 296

Creating Custom Work Queues 298

16 Notifications 301

Requesting Notifications 302

Sending Notifications 304

Enqueuing Notifications 305

Sending Notifications Between Applications 307

17 Network Access 311

Wrapping C Sockets 312

Connecting to Servers 314

Sharing Objects Over a Network 317

Finding Network Peers 320

Loading Data from URLs 323

18 Debugging Objective-C 327

Inspecting Objects 328

Recognizing Memory Problems 330

Watching Exceptions 333

Asserting Expectations 335

Logging Debug Messages 337

19 The Objective-C Runtime 339

Sending Messages by Name 340

Finding Classes by Name 342

Testing If an Object Understands a Method 343

Forwarding Messages 346

Finding Classes 349

Inspecting Classes 351

Creating New Classes 353

Adding New Instance Variables 356

Index 359