On June 2, 2014, Apple’s WWDC keynote address ended with a shocking announcement: “We have a new programming language.” This came as a huge surprise to the developer community, which was accustomed to Objective-C, warts and all, and doubted that Apple could ever possibly relieve them from the weight of its venerable legacy. The developer community, it appeared, had been wrong.
Having picked themselves up off the floor, developers immediately began to consider this new language — Swift — studying it, critiquing it, and deciding whether to use it. My own first move was to translate all my existing iOS apps into Swift; this was enough to convince me that, for all its faults, Swift deserved to be adopted by new students of iOS programming, and that my books, therefore, should henceforth assume that readers are using Swift.
Three years later, that decision has proven prophetic. Programmers of iOS have flocked to Swift in increasing numbers, and Swift itself has only improved. My iOS apps (such as Diabelli’s Theme, LinkSame, Zotz!, TidBITS News, and my Latin and Greek flashcard apps) have all been rewritten in Swift, and are far easier for me to understand and maintain than their Objective-C originals.
Xcode 9 comes with Swift 4. The language has evolved greatly in its details and in the nature of its integration with the Cocoa libraries that underlie iOS programming, but its spirit has remained constant. The Swift language is designed from the ground up with these salient features: ...