Introduction

When you pick up an iOS device and use it, you feel connected. Whether it be an iPad, an iPhone, or an iPod, the interface acts as an extension to your fingers; it is smooth, comfortable, and invites exploration. Other competing devices offer similar features, and even sport gadgets such as wraparound screens and trackpads, but they cannot match the user experience that is iOS.

iOS and its associated development tools have changed rapidly over the past few years. iOS 7 brought us a new user interface that used depth and translucency to keep users connected to their content and aware of the context in which they are accessing it. iOS 8 surprised everyone with a brand new language for developing apps: Swift. Alongside the introduction of iOS 9, Swift became an open source language, solidifying it as the future of development on Apple platforms and beyond.

Swift marks a dramatic change in the history of iOS and OS X development. With Swift, Apple has effectively retired the Objective-C language—used on Apple and NeXT platforms for over 25 years. Swift offers a friendlier development platform with more modern language features and tools. While in development for more than 4 years at Apple, by the time this book reaches you, Swift will have existed as a public programming language for a little over a year.

Unfortunately, there are some caveats to writing about a young language. Swift is rapidly evolving, and changes with each release of Apple’s development environment: Xcode. Code that is written in one version of Xcode sometimes breaks in the next. In the version of Swift shipping with iOS 9, for example, the language took syntax used for creating loops and changed its purpose entirely. Suddenly, code that was only a few months old stopped working.

Swift presents challenges, but I also think you’ll find that programming in Swift is fun (yes, really) and intuitive.

When creating Swift and the iOS development platform, Apple considered the entire application lifecycle. From the interface design tools, to the code that makes it function, to the presentation to the user, everything is integrated and works together seamlessly. As a developer, does this mean that there are rules to follow? Absolutely. But, by following these rules, you can create applications that are interactive works of art for your users to love—not software they will load and forget.

Through the App Store, Apple has created the ultimate digital distribution system for iOS applications. Programmers of any age or affiliation can submit their applications to the App Store for just the cost of a modest yearly Developer Membership fee. Games, utilities, and full-feature applications have been built for everything from pre-K education to retirement living. No matter what the content, with a user base as large as the iPhone, iPod touch, and iPad, an audience exists.

My hope is that this book brings iOS development to a new generation of developers. Sams Teach Yourself iOS 9 Application Development in 24 Hours provides a clear and natural progression of skills development, from installing developer tools and registering your device with Apple, to debugging an application before submitting it to the App Store. It’s everything you need to get started, in 24 one-hour lessons.

Developing an app won’t happen overnight, but with dedication and practice, you can be writing your first applications in a matter of days. The more time you spend working with the Apple developer tools, the more opportunities you’ll discover for creating new and exciting projects.

You should approach iOS 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’re likely to be disappointed. (The App Store is a crowded marketplace—albeit one with a lot of room—and competition for top sales is fierce.) However, if you focus on building useful and unique apps, you’re much more likely to find an appreciative audience.

That said, some things are expected of you, the reader. Specifically, you must be willing to invest in the learning process. If you just read each hour’s lesson without working through the tutorials, you will likely miss some fundamental concepts. In addition, you need to spend time reading the Apple developer documentation and researching the topics presented in this book. A vast amount of information on iOS development is available, but only limited space is available in this book. Therefore, this book covers what you need to forge your own path forward.

Unfortunately, this is not a complete reference for the iOS application programming interfaces (APIs), nor do I explicitly cover AppleTV or Apple Watch development; some topics just require much more space than this book allows. That said, this book should provide ample exposure to the tools and techniques that any iOS developer needs to be successful. In addition, the Apple developer documentation is available directly within the free tools you install in Hour 1, “Preparing Your System and iDevice for Development.” In many hours, you’ll find a section titled “Further Exploration.” This identifies additional related topics of interest. Again, a willingness to explore is an important quality in becoming a successful developer.

Each coding lesson is accompanied by project files that include everything you need to compile and test an example or, preferably, follow along and build the application yourself. Be sure to download the project files from this book’s website at http://teachyourselfios.com. If you have issues with any projects, view the posts on this site to see whether a solution has been identified.

In addition to the support website, you can follow along on Twitter! Search for #iOSIn24 on Twitter to receive official updates and tweets from other readers. Use the hashtag #iOSIn24 in your tweets to join the conversation. To send me messages via Twitter, begin each tweet with @johnemeryray.