The iOS 5 Developer's Cookbook

Erica Sadun is the bestselling author, coauthor, and contributor to several dozen books on programming, digital video and photography, and other technology topics. Sadun has authored dozens of iPhone-native applications, offers rapid-prototype consulting, and has blogged for many sites including Ars Technica, O’Reilly, and LifeHacker. She currently blogs regularly for TUAW. She holds a Ph.D. in Computer Science from Georgia Tech.

Preface xxvii

1 Introducing the iOS SDK 1

iOS Developer Programs 1

Online Developer Program 2

Standard Developer Program 2

Developer Enterprise Program 3

Developer University Program 3

Registering 3

Getting Started 3

Downloading the SDK 4

Development Devices 5

Simulator Limitations 6

Tethering 7

Understanding Model Differences 8

Screen Size 9

Camera 9

Audio 10

Telephony 10

Core Location and Core Motion Differences 10

Vibration Support and Proximity 11

Processor Speeds 11

OpenGL ES 11

Platform Limitations 12

Storage Limits 12

Data Access Limits 13

Memory Limits 13

Interaction Limits 16

Energy Limits 16

Application Limits 17

User Behavior Limits 18

SDK Limitations 18

Using the Provisioning Portal 19

Setting Up Your Team 19

Requesting Certificates 20

Registering Devices 20

Registering Application Identifiers 21

Provisioning 22

Putting Together iPhone Projects 23

The iPhone Application Skeleton 25

main.m 26

Application Delegate 28

View Controller 30

A Note about the Sample Code in This Book 31

iOS Application Components 32

Application Folder Hierarchy 32

The Executable 32

The Info.plist File 33

The Icon and Launch Images 34

Interface Builder Files 37

Files Not Found in the Application Bundle 37

IPA Archives 38

Sandboxes 38

Programming Paradigms 39

Object-Oriented Programming 39

Model-View-Controller 40

Summary 48

2 Objective-C Boot Camp 51

The Objective-C Programming Language 51

Classes and Objects 52

Creating Objects 54

Memory Allocation 54

Releasing Memory 55

Understanding Retain Counts with MRR 56

Methods, Messages, and Selectors 57

Undeclared Methods 57

Pointing to Objects 58

Inheriting Methods 59

Declaring Methods 59

Implementing Methods 60

Class Methods 62

Fast Enumeration 63

Class Hierarchy 63

Logging Information 64

Basic Memory Management 66

Managing Memory with MRR 67

Managing Memory with ARC 70

Properties 71

Encapsulation 71

Dot Notation 71

Properties and Memory Management 72

Declaring Properties 73

Creating Custom Getters and Setters 74

Property Qualifiers 76

Key-Value Coding 78

Key-Value Observing 79

MRR and High Retain Counts 79

Other Ways to Create Objects 80

Deallocating Objects 82

Using Blocks 84

Defining Blocks in Your Code 85

Assigning Block References 85

Blocks and Local Variables 87

Blocks and typedef 87

Blocks and Memory Management with MRR 88

Other Uses for Blocks 88

Getting Up to Speed with ARC 88

Property and Variable Qualifiers 89

Reference Cycles 92

Autorelease Pools 94

Opting into and out of ARC 95

Migrating to ARC 95

Disabling ARC across a Target 96

Disabling ARC on a File-by-File Basis 97

Creating an ARC-less Project from Xcode Templates 97

ARC Rules 98

Using ARC with Core Foundation and Toll Free Bridging 99

Casting between Objective-C and Core Foundation 99

Choosing a Bridging Approach 101

Runtime Workarounds 102

Tips and Tricks for Working with ARC 103

Crafting Singletons 103

Categories (Extending Classes) 104

Protocols 106

Defining a Protocol 106

Incorporating a Protocol 107

Adding Callbacks 107

Declaring Optional Callbacks 107

Implementing Optional Callbacks 108

Conforming to a Protocol 108

Foundation Classes 109

Strings 110

Numbers and Dates 115

Collections 117

One More Thing: Message Forwarding 123

Implementing Message Forwarding 123

House Cleaning 125

Super-easy Forwarding 126

Summary 126

3 Building Your First Project 127

Creating New Projects 127

Building Hello World the Template Way 129

Create a New Project 129

Introducing the Xcode Workspace 132

Review the Project 137

Open the iPhone Storyboard 138

Edit the View 140

Run Your Application 141

Using the Simulator 142

Simulator: Behind the Scenes 144

Sharing Simulator Applications 146

The Minimalist Hello World 146

Browsing the SDK APIs 149

Converting Interface Builder Files to Their Objective-C Equivalents 151

Using the Debugger 153

Set a Breakpoint 153

Open the Debugger 154

Inspect the Label 155

Set Another Breakpoint 156

Backtraces 157

Console 158

Add Simple Debug Tracing 158

Memory Management 158

Recipe: Using Instruments to Detect Leaks 159

Recipe: Using Instruments to Monitor Cached Object Allocations 162

Simulating Low-Memory Conditions 163

Analyzing Your Code 165

From Xcode to Device: The Organizer Interface 165

Devices 165

Summary 167

Provisioning Profiles 168

Device Logs 168

Applications 169

Console 169

Screenshots 170

Building for the iOS Device 170

Using a Development Provision 170

Enable a Device 171

Inspect Your Application Identifier 172

Set Your Device and Code Signing Identity 172

Set Your Base and Deployment SDK Targets 173

Compile and Run the Hello World Application 174

Signing Compiled Applications 175

Detecting Simulator Builds with Compile-Time

Checks 175

Performing Runtime Compatibility Checks 175

Pragma Marks 177

Collapsing Methods 178

Preparing for Distribution 178

Locating and Cleaning Builds 178

Using Schemes and Actions 179

Adding Build Configurations 181

About Ad Hoc Distribution 182

Building Ad Hoc Packages 183

Over-the-Air Ad Hoc Distribution 184

Building a Manifest 184

Submitting to the App Store 186

Summary 188

4 Designing Interfaces 191

UIView and UIWindow 191

Views That Display Data 192

Views for Making Choices 193

Controls 193

Tables and Pickers 195

Bars 195

Progress and Activity 196

View Controllers 196

UIViewController 197

UINavigationController 197

UITabBarController 198

Split View Controllers 198

Page View Controller 199

Popover Controllers 199

Table Controllers 199

Address Book Controllers 200

Image Picker 200

Mail Composition 200

Document Interaction Controller 200

GameKit Peer Picker 201

Media Player Controllers 201

View Design Geometry 201

Status Bar 202

Navigation Bars, Toolbars, and Tab Bars 203

Keyboards and Pickers 205

Text Fields 207

The UIScreen Class 207

Building Interfaces 207

Walkthrough: Building Storyboard Interfaces 208

Create a New Project 208

Add More View Controllers 208

Organize Your Views 209

Update Classes 210

Name Your Scenes 211

Edit View Attributes 211

Add Navigation Buttons 211

Add Another Navigation Controller 213

Name the Controllers 213

Tint the Navigation Bars 214

Add a Button 214

Change the Entry Point 215

Add Dismiss Code 215

Run the App 216

Popover Walkthrough 216

Add a Navigation Controller 216

Change the View Controller Class 217

Customize the Popover View 217

Make the Connections 218

Edit the Code 218

Walkthrough: Building an iOS-based Temperature Converter with IB 220

Create a New Project 220

Add Media 221

Interface Builder 221

Add Labels and Views 222

Enable Reorientation 223

Test the Interface 223

Add Outlets and an Action 223

Add the Conversion Method 225

Update the Keyboard Type 225

Connecting the iPad Interface 226

Walkthrough: Building a Converter Interface by Hand 227

Putting the Project Together 230

Walkthrough: Creating, Loading, and Using Hybrid Interfaces 230

Create a New XIB Interface File 231

Add a View and Populate It 231

Tag Your Views 231

Edit the Code 232

Designing for Rotation 233

Enabling Reorientation 233

Autosizing 235

Autosizing Example 237

Evaluating the Autosize Option 238

Moving Views 239

Recipe: Moving Views by Mimicking Templates 240

One More Thing: A Few Great Interface Builder Tips 243

Summary 245

5 Working with View Controllers 247

Developing with Navigation Controllers and Split Views 247

Using Navigation Controllers and Stacks 249

Pushing and Popping View Controllers 249

The Navigation Item Class 250

Modal Presentation 251

Recipe: Building a Simple Two-Item Menu 252

Recipe: Adding a Segmented Control 253

Recipe: Navigating Between View Controllers 255

Recipe: Presenting a Custom Modal

Information View 258

Recipe: Page View Controllers 262

Book Properties 262

Wrapping the Implementation 263

Exploring the Recipe 264

Recipe: Scrubbing Pages in a Page View Controller 269

Recipe: Tab Bars 271

Recipe: Remembering Tab State 275

Recipe: Building Split View Controllers 278

Recipe: Creating Universal Split View/Navigation Apps 282

Recipe: Custom Containers and Segues 284

Transitioning Between View Controllers 290

One More Thing: Interface Builder and Tab

Bar Controllers 291

Summary 292

6 Assembling Views and Animations 295

View Hierarchies 295

Recipe: Recovering a View Hierarchy Tree 297

Recipe: Querying Subviews 298

Managing Subviews 300

Adding Subviews 300

Reordering and Removing Subviews 300

View Callbacks 301

Recipe: Tagging and Retrieving Views 301

Using Tags to Find Views 302

Recipe: Naming Views 303

Associated Objects 304

Using a Name Dictionary 305

View Geometry 308

Frames 309

Transforms 310

Coordinate Systems 310

Recipe: Working with View Frames 311

Adjusting Sizes 312

CGRects and Centers 313

Other Utility Methods 314

Recipe: Randomly Moving a Bounded View 318

Recipe: Transforming Views 319

Display and Interaction Traits 320

UIView Animations 321

Building UIView Animation Transactions 322

Building Animations with Blocks 323

Conditional Animation 324

Recipe: Fading a View In and Out 324

Recipe: Swapping Views 326

Recipe: Flipping Views 327

Recipe: Using Core Animation Transitions 328

Recipe: Bouncing Views as They Appear 329

Recipe: Image View Animations 331

One More Thing: Adding Reflections to Views 332

Summary 335

7 Working with Images 337

Finding and Loading Images 337

Reading Image Data 339

Recipe: Accessing Photos from the iOS Photo Album 342

Working with the Image Picker 342

Recovering Image Edit Information 344

Recipe: Retrieving Images from Asset URLs 347

Recipe: Snapping Photos and Writing Them to the Photo Album 349

Choosing Between Cameras 351

Saving Pictures to the Documents Folder 353

Recipe: E-mailing Pictures 354

Creating Message Contents 354

Presenting the Composition Controller 356

Automating Camera Shots 358

Using a Custom Camera Overlay 358

Recipe: Accessing the AVFoundation Camera 359

Requiring Cameras 360

Querying and Retrieving Cameras 360

Establishing a Camera Session 361

Switching Cameras 363

Camera Previews 364

Laying Out a Camera Preview 364

EXIF 365

Image Geometry 365

Building Camera Helper 367

Recipe: Adding a Core Image Filter 368

Recipe: Core Image Face Detection 370

Extracting Faces 376

Recipe: Working with Bitmap Representations 377

Drawing into a Bitmap Context 378

Applying Image Processing 380

Image Processing Realities 382

Recipe: Sampling a Live Feed 384

Converting to HSB 386

Recipe: Building Thumbnails from Images 387

Taking View-based Screenshots 390

Drawing into PDF Files 390

Creating New Images from Scratch 391

Recipe: Displaying Images in a Scrollable View 392

Creating a Multi-Image Paged Scroll 395

Summary 396

8 Gestures and Touches 397

Touches 397

Phases 398

Touches and Responder Methods 399

Touching Views 399

Multitouch 400

Gesture Recognizers 400

Recipe: Adding a Simple Direct Manipulation Interface 401

Recipe: Adding Pan Gesture Recognizers 402

Recipe: Using Multiple Gesture Recognizers at Once 404

Resolving Gesture Conflicts 407

Recipe: Constraining Movement 408

Recipe: Testing Touches 409

Recipe: Testing Against a Bitmap 411

Recipe: Adding Persistence to Direct Manipulation Interfaces 413

Storing State 413

Recovering State 415

Recipe: Persistence Through Archiving 416

Recipe: Adding Undo Support 418

Creating an Undo Manager 418

Child-View Undo Support 418

Working with Navigation Bars 419

Registering Undos 420

Adding Shake-Controlled Undo Support 422

Add an Action Name for Undo and Redo (Optional) 422

Provide Shake-To-Edit Support 423

Force First Responder 423

Recipe: Drawing Touches Onscreen 424

Recipe: Smoothing Drawings 426

Recipe: Detecting Circles 429

Creating a Custom Gesture Recognizer 433

Recipe: Using Multitouch 435

Retaining Touch Paths 438

One More Thing: Dragging from a Scroll View 440

Summary 443

9 Building and Using Controls 445

The UIControl Class 445

Kinds of Controls 445

Control Events 446

Buttons 448

Adding Buttons in Interface Builder 449

Art 450

Connecting Buttons to Actions 451

Buttons That Are Not Buttons 452

Building Custom Buttons in Xcode 453

Multiline Button Text 455

Adding Animated Elements to Buttons 456

Recipe: Animating Button Responses 456

Recipe: Adding a Slider With a Custom Thumb 458

Customizing UISlider 459

Adding Efficiency 460

Appearance Proxies 460

Recipe: Creating a Twice-Tappable Segmented Control 465

Recipe: Subclassing UIControl 467

Creating UIControls 468

Tracking Touches 468

Dispatching Events 468

Working with Switches and Steppers 471

Recipe: Building a Star Slider 472

Recipe: Building a Touch Wheel 476

Adding a Page Indicator Control 478

Recipe: Creating a Customizable Paged Scroller 481

Building a Toolbar 486

Building Toolbars in Code 487

iOS 5 Toolbar Tips 489

Summary 489

10 Working with Text 491

Recipe: Dismissing a UITextField Keyboard 491

Text Trait Properties 492

Other Text Field Properties 493

Recipe: Adjusting Views Around Keyboards 495

Recipe: Dismissing Text Views with Custom Accessory Views 498

Recipe: Resizing Views with Hardware Keyboards 500

Recipe: Creating a Custom Input View 503

Recipe: Making Text-Input-Aware Views 508

Recipe: Adding Custom Input Views to Non-Text Views 511

Adding Input Clicks 511

Recipe: Building a Better Text Editor 513

Recipe: Text Entry Filtering 516

Recipe: Detecting Text Patterns 518

Rolling Your Own Expressions 518

Enumerating Regular Expressions 519

Data Detectors 520

Adding Built-in Type Detectors 520

Recipe: Detecting Misspelling in a UITextView 522

Searching for Text Strings 523

Recipe: Dumping Fonts 524

Recipe: Adding Custom Fonts to Your App 525

Recipe: Basic Core Text and Attributed Strings 526

Using Pseudo-HTML to Create Attributed Text 532

Recipe: Splitting Core Text into Pages 536

Recipe: Drawing Core Text into PDF 537

Recipe: Drawing into Nonrectangular Paths 539

Recipe: Drawing Text onto Paths 542

Drawing Text onto Bezier Paths 543

Drawing Proportionately 544

Drawing the Glyph 545

One More Thing: Big Phone Text 551

Summary 554

11 Creating and Managing Table Views 555

Introducing UITableView and UITableView Controller 555

Creating the Table 556

Recipe: Implementing a Basic Table 558

Populating a Table 558

Data Source Methods 559

Reusing Cells 560

Responding to User Touches 560

Selection Color 561

Changing a Table’s Background Color 561

Cell Types 562

Recipe: Building Custom Cells in Interface Builder 563

Adding in Custom Selection Traits 565

Alternating Cell Colors 565

Removing Selection Highlights from Cells 566

Creating Grouped Tables 567

Recipe: Remembering Control State for Custom Cells 567

Visualizing Cell Reuse 570

Creating Checked Table Cells 571

Working with Disclosure Accessories 572

Recipe: Table Edits 574

Displaying Remove Controls 575

Dismissing Remove Controls 575

Handling Delete Requests 576

Supporting Undo 576

Swiping Cells 576

Adding Cells 576

Reordering Cells 579

Sorting Tables Algorithmically 580

Recipe: Working with Sections 581

Building Sections 582

Counting Sections and Rows 583

Returning Cells 583

Creating Header Titles 584

Creating a Section Index 584

Delegation with Sections 585

Recipe: Searching Through a Table 586

Creating a Search Display Controller 586

Building the Searchable Data Source Methods 587

Delegate Methods 589

Using a Search-Aware Index 589

Customizing Headers and Footers 591

Recipe: Adding “Pull-to-Refresh” to Your Table 592

Coding a Custom Group Table 595

Creating Grouped Preferences Tables 595

Recipe: Building a Multiwheel Table 597

Creating the UIPickerView 598

Recipe: Using a View-based Picker 601

Recipe: Using the UIDatePicker 603

Creating the Date Picker 603

One More Thing: Formatting Dates 606

Summary 608

12 A Taste of Core Data 611

Introducing Core Data 611

Creating and Editing Model Files 612

Generating Class Files 614

Creating a Core Data Context 615

Adding Objects 616

Querying the Database 618

Detecting Changes 619

Removing Objects 619

Recipe: Using Core Data for a Table Data Source 620

Recipe: Search Tables and Core Data 623

Recipe: Integrating Core Data Table Views with Live Data Edits 625

Recipe: Implementing Undo/Redo Support with Core Data 628

Summary 632

13 Alerting the User 633

Talking Directly to Your User Through Alerts 633

Building Simple Alerts 633

Alert Delegates 634

Displaying the Alert 636

Kinds of Alerts 636

“Please Wait”: Showing Progress to Your User 637

Using UIActivityIndicatorView 638

Using UIProgressView 639

Recipe: No-Button Alerts 639

Building a Floating Progress Monitor 642

Recipe: Creating Modal Alerts with Run Loops 642

Recipe: Using Variadic Arguments with Alert Views 645

Presenting Simple Menus 646

Scrolling Menus 648

Displaying Text in Action Sheets 648

Recipe: Building Custom Overlays 649

Tappable Overlays 650

Recipe: Basic Popovers 650

Recipe: Local Notifications 652

Alert Indicators 654

Badging Applications 654

Recipe: Simple Audio Alerts 654

System Sounds 655

Vibration 656

Alerts 656

Delays 656

One More Thing: Showing the Volume Alert 658

Summary 659

14 Device Capabilities 661

Accessing Basic Device Information 661

Adding Device Capability Restrictions 662

Recipe: Recovering Additional Device Information 664

Monitoring the iPhone Battery State 666

Enabling and Disabling the Proximity Sensor 667

Recipe: Using Acceleration to Locate “Up” 668

Retrieving the Current Accelerometer Angle Synchronously 670

Calculate a Relative Angle 671

Working with Basic Orientation 671

Recipe: Using Acceleration to Move Onscreen Objects 672

Adding a Little Sparkle 675

Recipe: Core Motion Basics 676

Testing for Sensors 677

Handler Blocks 677

Recipe: Retrieving and Using Device Attitude 680

Detecting Shakes Using Motion Events 681

Recipe: Detecting Shakes via the Accelerometer 683

Recipe: Using External Screens 686

Detecting Screens 687

Retrieving Screen Resolutions 687

Setting Up Video Out 688

Adding a Display Link 688

Overscanning Compensation 688

VIDEOkit 688

One More Thing: Checking for Available Disk Space 692

Summary 693

15 Networking 695

Checking Your Network Status 695

Recipe: Extending the UIDevice Class for Reachability 697

Scanning for Connectivity Changes 700

Recovering IP and Host Information 702

Using Queues for Blocking Checks 705

Checking Site Availability 707

Synchronous Downloads 709

Asynchronous Downloads in Theory 713

Recipe: Asynchronous Downloads 715

Handling Authentication Challenges 721

Storing Credentials 722

Recipe: Storing and Retrieving Keychain Credentials 725

Recipe: Uploading Data 728

NSOperationQueue 728

Twitter 732

Recipe: Converting XML into Trees 733

Trees 733

Building a Parse Tree 734

Using the Tree Results 736

Recipe: Building a Simple Web-based Server 738

One More Thing: Using JSON Serialization 742

Summary 742

Index 745