The Code in This Book

The code in this book is 100% Swift. While it’s still a young language, Swift is clearly the direction in which Apple wants to move, so rather than trying to do both Swift and Objective-C and succeeding at neither, I elected to do this all in one language. The aforementioned book is also in Swift, so it serves as a great introduction to iOS in general and Swift specifically.

Now, Swift is a language that’s always changing, so it’s possible that things will break as new versions of Xcode come out. Fortunately, as a registered Pragmatic Bookshelf customer, you’re in luck! I’ll be keeping the book up to date and you’ll be notified whenever we release an update. As of this writing, the current version of Xcode is 7.2.1, targeting iOS 9.2 and watchOS 2.1. If that seems hilariously old to you, then it’s pretty likely that the syntax of Swift has changed. Xcode has some support for bringing things forward into new versions, so try using it to help. If you get stuck, let us know on the book’s forum or errata page. More on those next.

Although a later chapter in this book will discuss localization and internationalization for watchOS apps, the majority of the content in this book is in English with units of measure and formatting to American norms. Readers in other countries may need to enter slightly different values in some cases—for instance, entering “0,35” instead of “0.35” for a value in Xcode.