Sams teach yourself iphone application development in 24 hours, 2nd edition

HOUR 1 Preparing your System and iPhone for Development 2 Introduction to Xcode and the iPhone Simulator 3 Discovering Objective-C: The Language of Apple Platforms 4 Inside Cocoa Touch 5

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1 iPhone (Smartphone)—Programming 2 Application software—Development I Title II Title:

Teach yourself iPhone application development in 24 hours III Title: iPhone application

develop-ment in 24 hours

QA76.8.I64R39 2011

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2010035798Printed in the United States of America

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HOUR 1 Preparing your System and iPhone for Development

2 Introduction to Xcode and the iPhone Simulator

3 Discovering Objective-C: The Language of Apple Platforms

4 Inside Cocoa Touch

5 Exploring Interface Builder

6 Model-View-Controller Application Design

7 Working with Text, Keyboards, and Buttons

8 Handling Images, Animation, and Sliders

9 Using Advanced Interface Objects and Views

10 Getting the User’s Attention

11 Making Multivalue Choices with Pickers

12 Implementing Multiple Views with Toolbars and Tab Bars

13 Displaying and Navigating Data Using Table Views

14 Reading and Writing Application Data

15 Building Rotatable and Resizable User Interfaces

16 Using Advanced Touches and Gestures

17 Sensing Orientation and Motion

18 Working with Rich Media

19 Interacting with Other Applications

20 Implementing Location Services

21 Building Background-aware Applications

22 Building Universal Applications

23 Application Debugging and Optimization

24 Distributing Applications Through the App Store

Index

Introduction 1

Who Can Become an iPhone Developer? .1

Who Should Use This Book? .2

What Is (and Isn’t) in This Book? .2

HOUR 1: Preparing Your System and iPhone for Development 3 Welcome to the iOS Platform .3

Becoming an iOS Developer .7

Creating a Development Provisioning Profile .12

Developer Technology Overview .23

Summary .25

Q&A .25

Workshop .26

HOUR 2:Introduction to Xcode and the iPhone Simulator 27 Using Xcode .27

Using the iPhone Simulator .45

Further Exploration .50

Summary .50

Q&A .51

Workshop .51

HOUR 3: Discovering Objective-C: The Language of Apple Platforms 53 Object-Oriented Programming and Objective-C .53

Exploring the Objective-C File Structure .58

Objective-C Programming Basics .64

Memory Management .74

Further Exploration .77

Summary .77

Q&A .78

Workshop .79

Exploring the iOS Technology Layers .83

Tracing the iPhone Application Life Cycle .88

Cocoa Fundamentals .90

Exploring the iOS Frameworks with Xcode .98

Summary .102

Q&A .102

Workshop .103

HOUR 5: Exploring Interface Builder 105 Understanding Interface Builder .105

Creating User Interfaces .110

Customizing Interface Appearance .115

Connecting to Code .119

Further Exploration .126

Summary .127

Q&A .127

Workshop .128

HOUR 6: Model-View-Controller Application Design 129 Understanding the Model-View-Controller Paradigm .129

How Xcode and Interface Builder Implement MVC .131

Using the View-Based Application Template .135

Further Exploration .148

Summary .149

Q&A .149

Workshop .150

HOUR 7: Working with Text, Keyboards, and Buttons 151 Basic User Input and Output .151

Using Text Fields, Text Views, and Buttons .153

Setting Up the Project .154

Further Exploration .176

Summary .177

Q&A .177

Workshop .178

HOUR 8: Handling Images, Animation, and Sliders 179 User Input and Output .179

Creating and Managing Image Animations and Sliders .181

Further Exploration .196

Summary .197

Q&A .197

Workshop .198

HOUR 9: Using Advanced Interface Objects and Views 199 User Input and Output (Continued) .199

Using Switches, Segmented Controls, and Web Views .204

Using Scrolling Views .221

Further Exploration .227

Summary .227

Q&A .228

Workshop .228

HOUR 10:Getting the User’s Attention 231 Exploring User Alert Methods .231

Generating Alerts .235

Using Action Sheets .245

Using Alert Sounds and Vibrations .249

Further Exploration .253

Summary .254

Q&A .254

Workshop .255

HOUR 11:Making Multivalue Choices with Pickers 257 Understanding Pickers .257

Using Date Pickers .261

Implementing a Custom Picker View .270

Further Exploration .289

Summary .290

Q&A .290

Workshop .291

HOUR 12: Implementing Multiple Views with Toolbars and Tab Bars 293 Exploring Single Versus Multi-View Applications .293

Creating a Multi-View Toolbar Application .295

Building a Multi-View Tab Bar Application .307

Further Exploration .326

Summary .327

Q&A .327

Workshop .328

HOUR 13: Displaying and Navigating Data Using Table Views 329 Understanding Table Views and Navigation Controllers .329

Building a Simple Table View Application .332

Creating a Navigation-Based Application .344

Further Exploration .359

Summary .359

Q&A .360

Workshop .360

HOUR 14: Reading and Writing Application Data 363 Design Considerations .363

Reading and Writing User Defaults .366

Understanding the iPhone File System Sandbox .381

Implementing File System Storage .384

Further Exploration .404

Summary .405

Q&A .405

Workshop .406

HOUR 15: Building Rotatable and Resizable User Interfaces 407

Rotatable and Resizable Interfaces .407

Creating Rotatable and Resizable Interfaces with Interface Builder .411

Reframing Controls on Rotation .416

Swapping Views on Rotation .423

Further Exploration .429

Summary .430

Q&A .430

Workshop .431

HOUR 16:Using Advanced Touches and Gestures 433 Multitouch Gesture Recognition .434

Using Gesture Recognizers .435

Further Exploration .448

Summary .449

Q&A .449

Workshop .449

HOUR 17:Sensing Orientation and Motion 451 Understanding iPhone Motion Hardware .451

Accessing Orientation and Motion Data .454

Sensing Orientation .458

Detecting Tilt and Rotation .462

Further Exploration .471

Summary .472

Workshop .473

HOUR 18:Working with Rich Media 475 Exploring Rich Media .475

Preparing the Media Playground Application .478

Using the Movie Player .482

Creating and Playing Audio Recordings .486

Using the Photo Library and Camera .492

Accessing and Playing the iPod Library .495

Further Exploration .501

Summary .502

Q&A .502

Workshop .503

HOUR 19: Interacting with Other Applications 505 Extending Application Integration .505

Using Address Book, Email, and Maps… Oh My! .509

Further Exploration .526

Summary .527

Q&A .527

Workshop .527

HOUR 20: Implementing Location Services 529 Understanding Core Location .529

Creating a Location-Aware Application .534

Understanding the Magnetic Compass .541

Further Exploration .549

Summary .550

Q&A .550

Workshop .551

HOUR 21: Building Background-Aware Applications 553 Understanding iOS 4 Backgrounding .554

Disabling Backgrounding .558

Handling Background Suspension .559

Implementing Local Notifications .561

Using Task-Specific Background Processing .564

Completing a Long-Running Background Task .570

Further Exploration .576

Summary .577

Q&A .577

Workshop .577

Understanding the Universal Window-Based Application Template .581

Other Universal Application Tools .596

Further Exploration .598

Summary .599

Q&A .599

Workshop .599

HOUR 23:Application Debugging and Optimization 601 Debugging in Xcode .601

Monitoring with Instruments .614

Profiling with Shark .620

Further Exploration .627

Summary .627

Q&A .627

Workshop .628

HOUR 24:Distributing Applications Through the App Store 629 Preparing an Application for the App Store .630

Submitting an Application for Approval .642

Promoting Your Application .649

Exploring Other Distribution Methods .655

Summary .657

Q&A .657

Workshop .657

John Ray is currently serving as a Senior Business Analyst and Development Team

Manager for the Ohio State University Research Foundation He has written numerous

books for Macmillan/Sams/Que, including Using TCP/IP: Special Edition, Teach Yourself

Dreamweaver MX in 21 Days, Mac OS X Unleashed, and Teach Yourself iPad Development in 24 Hours As a Macintosh user since 1984, he strives to ensure that each project presents the

Macintosh with the equality and depth it deserves Even technical titles such as Using TCP/IP

contain extensive information about the Macintosh and its applications and have garnerednumerous positive reviews for their straightforward approach and accessibility to beginnerand intermediate users

You can visit his website at http://teachyourselfiphone.com or follow him on Twitter at

#iPhoneIn24

Dedication

This book is dedicated to everyone who makes me smile, even if only on occasion.

Thanks for keeping me stay sane during long nights of typing.

Acknowledgments

Thank you to the group at Sams Publishing—Laura Norman, Sandra Schroeder, Keith Cline,Matthew David—for providing amazing support during the creation of this book Your thor-oughness and attention to detail make the difference between a book that works and onethat bewilders

Thanks to my friends, family, and pets Deepest apologies to my fish tank I swear I’ll getyou working right soon

As the reader of this book, you are our most important critic and commentator We value

your opinion and want to know what we’re doing right, what we could do better, whatareas you’d like to see us publish in, and any other words of wisdom you’re willing to passour way

You can email or write me directly to let me know what you did or didn’t like about thisbook—as well as what we can do to make our books stronger

Please note that I cannot help you with technical problems related to the topic of this book, and that due to the high volume of mail I receive, I might not be able to reply to every message.

When you write, please be sure to include this book’s title and author as well as your nameand phone or email address I will carefully review your comments and share them with theauthor and editors who worked on the book

E-mail: feedback@quepublishing.com

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Over the past four years, Apple has changed the way we think about mobile computing.The iOS Platform has changed the way that we, the public, think about our mobile comput-ing devices With full-featured applications and an interface architecture that demonstratesthat small screens can be effective workspaces, the iPhone has become the smartphone ofchoice for users and developers alike.

Part of what makes the iPhone such a success is the combination of an amazing interfaceand an effective software distribution method With Apple, the user experience is key TheiOS is designed to be controlled with your fingers rather by using a stylus or keypad Theapplications are “natural” and fun to use, instead of looking and behaving like a clumsyport of a desktop app Everything from interface to application performance and battery lifehas been considered The same cannot be said for the competition

Through the App Store, Apple has created the ultimate digital distribution system for opers Programmers of any age or affiliation can submit their applications to the App Storefor just the cost of a modest yearly Developer Membership fee Games, utilities, and full-fea-ture applications have been built for everything from pre-K education to retirement living

devel-No matter what the content, with a user base as large as the iPhone, an audience exists

In 2010, Apple introduced the iPad and iPhone 4 platforms—bringing larger, faster, andhigher-resolution capabilities to the iOS Although these devices will only be a few months

“old” by the time you read this, they will already be in the hands of millions of users,eagerly awaiting the next great app

My hope is that this book will bring iOS development to a new generation of developers

Teach Yourself iPhone Development in 24 Hours provides a clear natural progression of skills

development, from installing developer tools and registering with Apple, to submitting anapplication to the App Store It’s everything you need to get started in 24 one-hour lessons

Who Can Become an iPhone Developer?

If you have an interest in learning, time to invest in exploring and practicing with Apple’sdeveloper tools, and an Intel Macintosh computer running Snow Leopard, you have every-thing you need to begin developing for the iPhone

Developing an application for the iPhone won’t happen overnight, but with dedication andpractice, you can be writing your first applications in a matter of days The more time youspend working with the Apple developer tools, the more opportunities you’ll discover for

You should approach iPhone application development as creating software that you want to

use, not what you think others want If you’re solely interested in getting rich quick, you’relikely to be disappointed (The App Store is a crowded marketplace—albeit one with a lot ofroom—and competition for top sales is fierce.) However, if you focus on building apps thatare useful and unique, you’re much more likely to find an appreciative audience

Who Should Use This Book?

This book targets individuals who are new to development for the iPhone and have ence using the Macintosh platform No previous experience with Objective-C, Cocoa, or theApple developer tools is required Of course, if you do have development experience, some

experi-of the tools and techniques may be easier to master, but the authors do not assume thatyou’ve coded before

That said, some things are expected of you, the reader Specifically, you must be willing toinvest in the learning process If you just read each hour’s lesson without working through thetutorials, you will likely miss some fundamental concepts In addition, you need to spend timereading the Apple developer documentation and researching the topics presented in this book.There is a vast amount of information on iPhone development available, and only limitedspace in this book This book covers what you need to forge your own path forward

What Is (and Isn’t) in This Book?

The material in this book specifically targets iOS release 4 Much of what you’ll be learning

is common to all the iOS releases, but this book also covers several important advances in

4, such as Gestures, embedded video playback, multitasking, universal (iPhone/iPad) cations, and more!

appli-Unfortunately, this is not a complete reference for the iPhone APIs; some topics just requiremuch more space than this book allows Thankfully, the Apple developer documentation isavailable directly within the free tools you’ll be downloading in Hour 1, “Preparing YourSystem and iPhone for Development.” In many hours, you’ll find a section titled “FurtherExploration.” This will identify additional related topics of interest Again, a willingness toexplore is an important quality in becoming a successful iPhone developer!

Each coding lesson is accompanied by project files that include everything you need to pile and test an example or, preferably, follow along and build the application yourself Besure to download the project files from the book’s website at http://teachyourselfiphone.com

com-In addition to the support website, you can follow along on Twitter! Search for #iPhonecom-In24

on Twitter to receive official updates and tweets from other readers Use the hashtag

#iPhoneIn24 in your tweets to join the conversation To send me messages via Twitter, begineach tweet with @johnemeryray

Preparing Your System and

iPhone for Development

What You’ll Learn in This Hour:

What makes an iPhone an iPhone

Where to get the tools you need to develop for the iPhone

How to join the iOS Developer Program

The need for (and use of) provisioning profiles

What to expect during the first few hours of this book

The iPhone opens up a whole realm of possibilities for developers—a multitouch interface,always-on Internet access, video, and a whole range of built-in sensors can be used to cre-ate everything from games to serious productivity applications Believe it or not, as a newdeveloper, you have an advantage You will be starting fresh, free from any preconceivednotions of what is possible in a handheld application Your next big idea may wellbecome the next big thing on Apple’s App Store

This hour will get you prepared for iPhone development You’re about to embark on theroad to becoming an iPhone developer, but ‘you need to do a bit of prep work before youstart coding

Welcome to the iOS Platform

If you’re reading this book, you probably already have an iPhone, and that means youalready understand how to interact with its interface Crisp graphics, amazing responsive-ness, multitouch, and hundreds of thousands of apps—this just begins to scratch the sur-face As a developer, however, you’ll need to get accustomed to dealing with a platformthat, to borrow a phrase from Apple, forces you to “think different.”

Display and Graphics

The iPhone screen is 320×480 points—giving you a limited amount of space to ent your application’s content and interface (see Figure 1.1) Notice that I said

pres-“points”, and not pixels! Prior to the release of the iPhone 4’s Retina display, the

iPhone was 320×480 pixels Now, the actual resolution of an iOS device is abstractedbehind a scaling factor This means that while you will be working the numbers

320×480 for positioning elements, you may have more pixels than that The iPhone

4, for example, has a scaling factor of 2, which means that it is really a(320×2)×(480×2) or 640×960 resolution device Although that might seem like quite

a bit of screen real estate, remember that all these pixels are displayed in a screenthat is roughly 3.5-inch” diagonal

Know? We’ll look more at how scaling factors work when we position objects on thescreen throughout the book The important thing to know is that when you’re

build-ing your applications, the iOS will automatically take the scalbuild-ing factor into play todisplay your apps and their interfaces at the highest possible resolution with

rarely any additional work on your part!

Although this might seem limiting, consider that desktop computers only recentlyexceeded this size, and many websites are still designed for 800×600 In addition,

By the

Way

the iPhone’s display is dedicated to the currently running application You will have

one window to work in You can change the content within that window, but the

desktop and multiwindow application metaphors are gone

The screen limits aren’t a bad thing As you’ll learn, the iPhone development tools

give you plenty of opportunities to create applications with just as much depth as

your desktop software—albeit with a more structured and efficient interface design

The graphics that you display on your screen can include complex animated 2D

and 3D displays thanks to the OpenGL ES implementation available on all iPhone

models OpenGL is an industry standard for defining and manipulating graphic

images that is widely used when creating games The iPhone 3GS and 4 improve

these capabilities with an updated 3D chipset and more advanced version of

OpenGL (ES 2.0), but all the models have very respectable imaging abilities

Application Resource Constraints

As with the HD displays on our desktops and laptops, we’ve grown accustomed to

processors that can work faster than we can click The iPhone uses a ~400MHz ARM

in the early models, a ~600MHz version in the 3GS, and a 1GHz A4 in the iPhone 4

The A4 is a “system on a chip” that provides CPU, GPU, and other capabilities to the

device and is the first Apple-designed CPU to be used in quite a while

Apple has gone to great lengths to keep the iPhone responsive regardless of what

you’re doing Unfortunately, that means that unlike the Mac OS, your iPhone’s

capability to multitask is limited In iOS 4, Apple has created a limited set of

multi-tasking APIs for very specific situations These enable you to perform some tasks in

the background, but your application can never assume that it will remain running

The iOS preserves the user experience beyond above all else

Another constraint that you need to be mindful of is the available memory In the

original and iPhone 3G devices, 128MB of RAM is available for the entire system,

including your application There is no virtual memory, so you must carefully manage

the objects that your application creates In the iPhone 3GS Apple upped the ante to

256MB and, with the iPhone 4, Apple has graciously provided 512MB! This is great

for us, but keep in mind that there are no RAM upgrades for earlier models!

Throughout the book, you’ll see reminders to “release” memory when you’re done

using it Even though you might get tired of seeing it, this is a very important

process to get used to

The iPhone has the ability to always be connected to the Internet via a cellularprovider (such as AT&T in the United States) This wide-area access is supplementedwith built-in WiFi and Bluetooth in all iPhone models WiFi can provide desktop-likebrowsing speeds within the range of a wireless hot spot Bluetooth, on the otherhand, can be used to connect a variety of peripheral devices to your iPhone, includ-ing a keyboard!

As a developer, you can make use of the Internet connectivity to update the content

in your application, display web pages, and create multiplayer games The onlydrawback is that applications that rely heavily on 3G data usage stand a greaterchance of being rejected from the App Store These restrictions have been lessened inrecent months, but it is still a point of frustration for developers

Input and Feedback

The iPhone shines when it comes to input and feedback mechanisms and your ability

to work with them You can read the input values from the capacitive multitouch(five-finger!) screen, sense motion and tilt via the accelerometer and gyroscope (iPhone4), determine where you are using the GPS (3G/3GS), see which way you’re facing withthe digital compass (3GS and iPhone 4), and understand how the phone is being usedwith the proximity and light sensors The phone itself can provide so much data toyour application about how and where it is being used that the device itself trulybecomes a controller of sorts—much like (but surpassing!) the Nintendo Wii

The iPhone also supports capturing pictures and video (3GS and iPhone 4) directlyinto your applications, opening a realm of possibilities for interacting with the realworld Already applications are available that identify objects you’ve taken pictures

of and that find references to them online (such as the Amazon Mobile app).Finally, for each action your user takes when interacting with your application, youcan provide feedback This, obviously, can be visible feedback on the screen, or itcan be high-quality audio and force feedback via vibration As a developer, you canleverage all these capabilities (as you’ll learn in this book)

That wraps up our quick tour of the iOS platform Never before has a single devicedefined and provided so many capabilities for a developer As long as you thinkthrough the resource limitations and plan accordingly, a wealth of developmentopportunities awaits you

Did you

Know?

Although this book targets the iPhone specifically, nearly all the information

car-ries over to development for the iPod Touch and iPad These systems differ in

capabilities, such as support for a camera and GPS, but the development

tech-niques are otherwise identical

Becoming an iOS Developer

Being an iPhone developer requires more than just sitting down and writing a

pro-gram You need a modern Intel Macintosh desktop or laptop running Snow Leopard

and at least 6GB of free space on your hard drive The more screen space you have

on your development system, the easier it will be to switch between the coding,

design, simulation, and reference tools that you’ll need to be using That said, I’ve

worked perfectly happily on a 13-inch MacBook Pro, so an ultra-HD multimonitor

setup certainly isn’t necessary

So assuming you already have a Mac, what else do you need? The good news is that

there isn’t much more, and it won’t cost you a cent to write your first application.

Joining the Apple Developer Program

Despite somewhat confusing messages on the Apple website, there really is no fee

associated with joining the Apple Developer Program, downloading the iOS SDK

(Software Development Kit), writing iPhone applications, and running them on

Apple’s iPhone Simulator

Limitations do apply, however, to what you can do for free If you want to have

early access to beta versions of the iOS and SDK, you must be a paid member If you

want to load the applications you write on a physical iPhone device or distribute

them via the App Store, you’ll also need to pay the membership fee Most

applica-tions in this book will work just fine on the simulator provided with the free tools, so

the decision on how to proceed is up to you

Perhaps you aren’t yet sure whether the paid program is right for you Don’t worry;

you can upgrade at any time I recommend starting out with the free program and

upgrading after you’ve had a chance to write a few sample applications and to run

them in the simulator

Obviously, things such as motion sensor input and GPS readings can’t be

accu-rately presented in the simulator, but these are special cases and aren’t needed

until later in this book

Did you

Know?

By the

Way

If you don’t yet have an Apple ID, click the Register link, and then click Get Started

on the subsequent page When the registration starts, choose Create an Apple ID inthe first step, as shown in Figure 1.3

If you choose to pay, the paid Developer Program offers two levels: a standard gram ($99) for those who will be creating applications that they want to distributefrom the App Store, and an enterprise program ($299) for large (500+ employee)

pro-companies that want to develop and distribute applications in-house but not

through the App Store Chances are, the standard program is what you want

The standard ($99) program is available for both companies and individuals In caseyou want to publish to the App Store with a business name, you’ll be given the option

of choosing a standard “individual” or “company” program during the registration

Registering as a Developer

Big or small, free or paid, your venture into iPhone development begins on Apple’swebsite To start, visit the Apple iPhone Dev Center (http://developer.apple.com/iphone), shown in Figure 1.2

If you already have an Apple ID from using iTunes or other Apple services, lations, you’re almost done! Use the Log In button to access your account, agree toApple’s developer terms, and provide a few pieces of additional information for yourdeveloper profile You’ll immediately be granted access to the free developer resources!

FIGURE 1.3

You’ll use anApple ID toaccess all thedeveloperresources

The registration process walks you through the process of creating a new Apple ID

and collects information about your development interests and experience, as

shown in Figure 1.4

Upon completion of the registration, Apple verifies your email address by sending

you a clickable link to activate your account

FIGURE 1.4

The multistepregistrationprocess collects

a variety ofinformationabout yourdevelopmentexperience

Joining a Paid Developer Program

After you have a registered and activated Apple ID, you can decide to join a paid gram or to continue using the free resources If you choose to join a paid program,again point your browser to the iPhone Dev Center (http://developer.apple.com/iphone)and click the Register link Choose Use an Existing Apple ID for the Developer Programoption, shown in Figure 1.3

pro-On the page that appears, look for the Join Today link and click it The registrationtool will now guide you through applying for the paid programs, including choosingbetween the standard and company options, as shown in Figure 1.5

to the iPhone Dev Center and clicking the Check Your Enrollment Status Now link.Click the Register link to create a new free Developer Membership, or follow thelinks in the iOS Developer Program section (currently http://developer.apple.com/iphone/program) to join a paid program

Installing the iOS Developer Tools

After you’ve registered your Apple ID, you can immediately download the currentrelease version of the iOS developer tools directly from the iPhone Dev Center

Did you

Know?

(http://developer.apple.com/iphone) Just click the Download link and sit back while

your Mac downloads the massive (~2.5GB) SDK disk image

If you have the free Developer Membership, you’ll likely see just a single SDK to

download (the current release version of the development tools) If you’ve become

a paid program member, you may see additional links for different versions of the

SDK (3.2, 4.0, and so on) The examples in this book are based on the 4.0+

series of SDKs, so be sure to choose that option if presented

When the download completes, open the resulting disk image, and double-click the

Xcode and iPhone SDK for Snow Leopard icon Doing so launches the Mac OS X

Installer application, which will assist you in the installation You don’t have to

change any of the defaults for the installer, so just read and agree to the software

license and click Continue to proceed through the steps

Unlike most applications, the Apple developer tools are installed in a folder called

Developer located at the root of your hard drive Inside the Developer folder are

dozens of files and folders containing developer frameworks, source code files,

exam-ples, and of course, the developer applications themselves Nearly all your work in

this book will start with the application Xcode, located in the Developer/Applications

folder (see Figure 1.6)

FIGURE 1.6

Most of yourwork with thedeveloper toolswill start in theDeveloper/Applicationsfolder

Although we won’t get into real development for a few more hours, we will be

con-figuring a few options in Xcode in the next section, so don’t forget where it is!

Creating a Development Provisioning Profile

Even after you’ve obtained an Apple Developer Membership, joined a paidDeveloper Program, and downloaded and installed the iOS development tools, youstill won’t be able to run on your iPhone any applications that you write! Why?Because you haven’t created a development provisioning profile yet

In many development guides, this step isn’t covered until after development begins

In my mind, once you’ve written an application, you’re going to want to ately run it on the iPhone Why? Because it’s just cool to see your own code running

immedi-on your own device!

What’s a Development Provisioning Profile?

Like it or not, Apple’s current approach to iOS development is to make absolutelycertain that the development process is controlled—and that groups can’t just dis-tribute software to anyone they want The result is a rather confusing process thatties together information about you, any development team members, and yourapplication into a “provisioning profile.”

A development provisioning profile identifies the developer who may install anapplication, an ID for the application being developed, and the “unique device

identifiers” for each iPhone that will run the application This is only for the

develop-ment process When you are ready to distribute an application via the App Store or

to a group of testers (or friends!) via ad hoc means, you’ll need to create a separate

“distribution” profile Because we’re just starting out, this isn’t something you needright away We talk more about distribution profiles in Hour 24, “DistributingApplications Through the App Store.”

Generating and Installing a Development Provisioning Profile

Creating a provisioning profile can be frustrating and seem outrageously convoluted.Apple has streamlined the process tremendously with an online DevelopmentProvisioning Assistant, but we still have to jump through some hoops Let’s bite thebullet and get through this!

Getting Your iPhone Unique Device Identifier

To run your application on a real iPhone, you need the ID that uniquely identifiesyour iPhone from the thousands of other iPhones To find this, first make sure thatyour device is connected to your computer, and then launch Xcode from the

Developer/Applications folder When Xcode first launches, immediately choose

Window, Organizer from the menu The Organizer utility slightly resembles iTunes

in its layout You should see your iPhone listed in the far-left column of the

Organizer under the Devices section Click the icon to select it, and then click the

Use for Development button Your screen should now resemble Figure 1.7

FIGURE 1.7

First, grab the

ID of youriPhone

The Identifier field is the unique device ID that we’re looking for Go ahead and copy

it to the Clipboard You’ll need to paste it into the Provisioning Assistant shortly

Starting the Provisioning Assistant

Next, head to the Apple website and the iOS Dev Center (http://developer.apple

com/ios) Make sure that you’ve logged in to the site, and then click the

Provisioning Portal link, currently located in the upper-right side of the page The

Provisioning Portal is designed to give you access to the tools you need to create

pro-visioning and distribution profiles It also includes the Development Propro-visioning

Assistant, which is the web utility that will make our lives much easier Click the

Launch Assistant button (see Figure 1.8)

The assistant will launch in your web browser and display a short splash screen

Click the Continue button to begin

multiple applications, however, they can share keychain data.

For the purposes of this book, there’s no reason the tutorial apps can’t share a singleApp ID, so create a new ID named anything you want If you have already createdApp IDs in the past, you’ll be given the option to choose an existing ID I’m creating

a new App ID, Tutorials, as shown in Figure 1.9 Enter the ID and click Continue tomove on

Assigning a Development Device

Next you are asked to assign a development device, as shown in Figure 1.10 Thisdevice ID identifies which iPhone will be allowed to run the applications you create.Enter a meaningful description for the device (“Johns iPhone,” for example), andthen paste the string you copied from the Xcode organizer into the Device ID field.Click Continue to move on

Note that as with the App IDs, if you’ve already used a device ID in the past, you

will be given the option of simply selecting it from a drop-down list

FIGURE 1.9

An App ID can

be used for asingle applica-tion or group of

applications.

FIGURE 1.10

Assign a devicethat can runyour application

Generating a Certificate Signing Request

Now things are getting fun The next step takes place outside of your browser.Leaving the Development Provisioning Assistant open, go to the Applications/Utilitiesfolder on your hard drive and open the Keychain Access utility Choose KeychainAccess, Certificate Assistant, Request a Certificate from a Certificate Authority fromthe menu (see Figure 1.11)

Uploading the Certificate Signing Request

Return to the Development Provisioning Assistant in your web browser Click

Continue until you are prompted to submit the certificate signing request that you

just generated (see Figure 1.13) Click the Choose File button so that you can select

the request file, and then click Continue to upload it

FIGURE 1.13

Upload the tificate signingrequest toApple

cer-Naming and Generating the Provisioning Profile

We’re almost done! After uploading the request, you’ll be prompted to name the

provisioning profile (see Figure 1.14) Because this profile contains information that

can potentially identify individual phones and applications, you should choose

something relevant to how you intend to use it In this case, I’m only interested in

using it as a generic development profile for all of my apps, so I’m naming it iPhone

Development Profile Not very creative, but it works

Click the Generate button to create your provisioning profile This may take 20 to 60

seconds, so be patient The screen will eventually refresh to show the final profile

information, as shown in Figure 1.15

Our final steps will be downloading and installing the profile, and downloading and

installing a security certificate that will be associated with the profile

Downloading the Development Provisioning Profile and Certificate

At this point, your profile has been generated, along with a security certificate that can beused to uniquely associate your applications with that profile All that remains is down-loading and installing them Click the Continue button to access the provisioning profiledownload screen, as shown in Figure 1.16 Click the Download Now button to save theprofile to your Downloads folder (file extension mobileprovision)

As much as I hate to say it, the next thing to do is to ignore the onscreen instructions—

the installation process that Apple describes in the assistant isn’t the most efficient

route Instead, click the Continue button until you are given the option of downloading

the development certificate, as shown in Figure 1.17

Click the Download button to download the certificate file (file extension cer) to

your Downloads folder You are now finished with the Provisioning Assistant and

can safely exit

FIGURE 1.16

Download theprovisioning profile

FIGURE 1.17

Download thedevelopmentcertificate

Installing the Development Provisioning Profile and Certificate

To install the profile and certificate, we just need to exercise our double-click skills.First, install the development certificate by double-clicking it Doing so opens KeychainAccess and prompts you for the keychain where the certificate should be installed.Choose the login keychain, and then click Add, as demonstrated in Figure 1.18

Did you

Know?

After you have a development machine configured, you can easily configure other

computers using the Developer Profile item in the Xcode organizer The Export

Developer Profile and Import Developer Profile buttons will export (and

subse-quently import) all your developer profiles/certificates in a single package

But Wait… I Have More Than One iOS Device!

The Development Provisioning Assistant helps you create a provisioning profile for

a single iPhone, iPad, or iPod Touch device But what if you have multiple devices

that you want to install onto? No problem You’ll need to head back to the

Provisioning Portal and click the Devices link on the left side of the page From

there, you can add additional devices that will be available to your profile

Next, click the Provisioning link, also on the left side of the page, and use the Edit

link to modify your existing profile to include another iPhone, as demonstrated in

Figure 1.20

Finally, you’ll need to click the Download link to redownload the modified profile

and then import it into Xcode so that the additional device is available

FIGURE 1.20

Add additionaldevices to aprovisioning pro-file within theweb portal.Remember toredownload theprofile andinstall it!

Testing the Profile with an iPhone App

It seems wrong to go through all of that work without some payoff, right? For a

real-world test of your efforts, let’s actually try to run an application on your iPhone If

you haven’t downloaded the project files to your computer, now is a good time to

visit http://teachyourselfiphone.com and download the archives

By the

Way

Within the Hour 1 Projects folder, open the Welcome folder Double-clickWelcome.xcodeproj to open a simple application in Xcode After the project opens,your display should be similar to Figure 1.21

Xcode will install the correct provisioning profile on your device, and, after a fewseconds, the application should be installed and launched on your iPhone, as seen

in Figure 1.22

You can now exit Xcode and quit the Welcome application on your iPhone

When you clicked Build and Run, the Welcome application was installed and

start-ed on your iPhone It will remain there until you remove it manually Just touch andhold the Welcome icon until it starts wiggling, and then delete the application asyou would any other Applications installed with your development certificate willstop working when the certificate expires (120 days after it was issued)

Developer Technology Overview

Over the course of the next few hours, you will be introduced to the technologies

that you’ll be using to create iPhone applications The goal is to get you up to speed

on the tools and technology, and then you can start actively developing This means

you’re still a few hours away from writing your first app, but when you start coding,

you’ll have the necessary background skills and knowledge to successfully create a

wide variety of applications

The Apple Developer Suite

In this hour, you downloaded and worked with the Xcode application This is just

one piece (albeit an important piece) of the developer suite that you will be using

throughout this book Xcode, coupled with Interface Builder and the iPhone

Simulator, will make up your development environment These three applications

are so critical, in fact, that two hours (2 and 4) are devoted to covering them

It’s worth mentioning that almost every iPhone, iPad, iPod, and Macintosh

applica-tion you run, whether created by a single developer at home or a huge company, is

built using the Apple developer tools This means that you have everything you

need to create software as powerful as any you’ve ever run

Later in the book, you’ll be introduced to additional tools in the suite that can help

you debug and optimize your application

FIGURE 1.22

Congratulations,you’ve justinstalled yourfirst home-grown iPhoneapplication!

By the

Way During the writing of this book, Apple released a “developer preview” of Xcode 4.

Because there is no known release schedule for Xcode 4, and you can’t yet use it

to build real applications, we are writing with the tried-and-true Xcode 3.2 Forthose who want to make the transition, we’ll be providing an online introduction toXcode 4 (as soon as it is publicly available) at the book’s support site:

http://teachyourselfiphone.com/ Be sure to check it out!

Objective-C

Objective-C is the language that you’ll be using to write your applications It vides the structure for our applications and is to control the logic and decision mak-ing that goes on when an application is running

pro-If you’ve never worked with a programming language before, don’t worry Hour 3,

“Discovering Objective-C: The Language of Apple Platforms,” covers everything youneed to get started Developing for the iPhone in Objective-C is a unique programmingexperience, even if you’ve used other programming languages in the past The lan-guage is unobtrusive and structured in a way that makes it easy to follow After yourfirst few projects, Objective-C will fade into the background, letting you concentrate onthe specifics of your application

Cocoa Touch

While Objective-C defines the structure for iPhone applications, Cocoa Touch defines

the functional building blocks, called classes, that can make the iPhone do certain

things Cocoa Touch isn’t a “thing,” per se, but a collection of interface elements, datastorage elements, and other handy tools that you can access from your applications

As you’ll learn in Hour 4, “Inside Cocoa Touch,” you can access literally hundreds ofdifferent Cocoa Touch classes and do thousands of things with them This book cov-ers quite a few of the most useful classes and gives you the pointers you need toexplore even more on your own

Model-View-Controller

The iOS platform and Macintosh use a development approach called Controller (MVC) to structure applications Understanding why MVC is used and thebenefits it provides will help you make good decisions in structuring your most com-plex applications Despite the potentially complicated-sounding name, MVC is real-

Model-View-ly just a way to keep your application projects arranged so that you can easiModel-View-lyupdate and extend them in the future You’ll take a more detailed look at MVC inHour 6, “Model-View-Controller Application Design.”

This hour introduced you to the iOS platform, its capabilities, and its limitations

You learned about the iPhone’s graphic features, RAM size, and the various sensors

that you can use in your applications to create uniquely “aware” experiences We

also discussed the Apple iPhone developer tools, how to download and install them,

and the differences between the varying pay-for developer programs To prepare you

for actual on-phone development, you explored the process of creating and

installing a Development Provisioning Profile in Xcode and even installed an

appli-cation on your phone

The hour wrapped up with a quick discussion of the development technologies that

make up the first part of the book and form the basis for all the iPhone

develop-ment you’ll be doing

Q&A

Q I thought the iPhone had at minimum 16GB of RAM in the low-end model

and 32GB on the high-end model Doesn’t it?

A The “memory” capabilities for the iPhone that are advertised to the public are

the storage sizes available for applications, songs, and so forth It is separate

from the RAM that can be used for executing programs If Apple implements

virtual memory in a future version of iOS, it is possible that the larger storage

could be used for increasing available RAM

Q What platform should I target for development?

A That depends on your goals If you want to reach the largest audience, consider

a universal application that works on the iPhone, iPad, and iPod Touch We

examine this development possibility later in Hour 22, “Building Universal

Applications.” If you want to make use of the most capable hardware, you can

certainly target the unique capabilities of the iPhone 4, but you will potentially

be limiting the size of your customer base

Q Why isn’t the iPhone (and iOS platform) open?

A Great question Apple has long sought to control the user experience so that it

remains “positive” regardless of how users have set up their device, be it a

Mac, an iPhone, or an iPhone By ensuring that applications can be tied to a

developer and enforcing an approval process, Apple attempts to limit the

potential for a harmful application to cause damage to data or otherwise

neg-atively impact the user Whether this is an appropriate approach, however, is

open to debate

Workshop Quiz

1 What is the resolution of the iPhone screen?

2 What is the cost of joining an individual iOS Developer Program?

3 What language will you use when creating iPhone applications?

Answers

1 Trick question The iPhone screen has 320×480 points, but you can’t tell howmany pixels unless you multiply by the scaling factor The iPhone 4 has ascaling factor of 2; all other models have a scaling factor of 1

2 The Developer Program costs $99 a year for the individual option

3 Objective-C will be used for iPhone development

Activities

1 Establish an Apple Developer Membership and download and install the oper tools This is an important activity that, if you didn’t follow along in thecourse of the hour, should be completed before starting the next hour’s lesson

devel-2 Review the resources available in the iOS Dev Center Apple has publishedseveral introductory videos and tutorials that supplement what you’ll learn inthis book

Introduction to Xcode and the iPhone Simulator

What You’ll Learn in This Hour:

How to create new projects in Xcode

Code editing and navigation features

Where to add classes and resources to a project

How to modify project properties

Compiling for the iPhone and the iPhone Simulator

How to interpret error messages

Features and limitations of the iPhone Simulator

The core of your work in the Apple Developer Suite will be spent in three applications:Xcode, Interface Builder, and the iPhone Simulator This trio of apps provides all the toolsthat you need to design, program, and test applications for the iPhone And, unlike otherplatforms, the Apple Developer Suite is entirely free!

This hour walks you through the basics you need to work within two of the three components—Xcode and the iPhone Simulator—and you’ll get some hands-on practice working with each

We cover the third piece, Interface Builder, in Hour 5, “Exploring Interface Builder.”

Using Xcode

When you think of coding—actually typing the statements that will make your iPhone meetApple’s “magical” mantra—think Xcode Xcode is the IDE, or integrated development envi-ronment, that manages your application’s resources and lets you edit the code that ties thedifferent pieces together