During the WWDC2014 keynote, Apple made the exciting announcement that a brand new programming language was nearing release. Within 24 hours, 370,000 developers had downloaded Apple’s new book entitled “The Swift Programming Language” from the iBooks Store. In this post, we’ll introduce Swift and it’s major language features at a high level. Future posts will delve deeper into specific topics.
Swift is intended to be a simpler, more elegant, safer, and more modern programming language compared to it’s predecessor. It is expected that Swift will gradually replace Objective-C as the de facto programming language for iOS and OS X applications. In order to support a gradual transition, Swift is fully interoperable with Objective-C. You can easily write programs that consist of a blend of both Swift and Objective-C code. There are a few caveats, such as the fact that you cannot currently subclass a Swift class in Objective-C. These caveats may come into play if you plan on doing a gradual migration of your code from Objective-C to Swift.
Swift supports every core data type that you would expect: signed and unsigned integers in standard sizes (8,16,32,64), floating points, strings, arrays, structs, enums, classes, interfaces, and even generics. Additional interesting concepts built into the language include tuples, optionals, and closures.
Swift constants and variables are declared with the let and var keywords, respectively. Swift is strongly typed, although Apple believes that explicit type annotation is not necessary in many cases, due to Swift’s sophisticated type inferencing capabilities. In the simple example below, the myInt constant will be strictly enforced as an Int type throughout the program. The variable myDouble will be strictly treated as a Double. More specific types are created with type annotations using a colon, as shown in the myShort and myFloat examples below.
let myInt = 10 // inferred and enforced as Int
var myDouble = 10.1 // inferred and enforced as Double
let myShort: UInt8 = 10 // Smaller range
var myFloat: Float = 10.1 // Less precision
Although it is not real-world applicable, the Swift team enjoys pointing out that it only takes 1 line of code to have a complete, stand-alone, executable program.
println(“Welcome to Swift”)
A main() or equivalent entry point is not strictly necessary, since execution will begin with code defined at the global scope. One simplification that I can’t seem to train my brain to accept is that semi-colons are not required, unless you are placing multiple statements on a single line. Finally, it is not necessary to explicitly include external libraries for basic functionality such as printing output to the console.
These are “tip of the iceberg” examples of how Swift better represents Apple’s overall mantra of making things simple and intuitive. Memory management also occurs automatically in Swift, eliminating the need to track allocations and releases.
Version 6 of Apples Xcode IDE includes full support for Swift. There is even a slick new feature called Playgrounds, which allows “interactive programming” where you see instant results of your code as you are developing it, without requiring you to compile and run a complete project.
It’s important to remember that Swift is barely beginning its life cycle as a programming language. New OS X and iOS developers will still need to learn and understand Objective-C in order to be truly effective. That said, Swift represents an important step for Apple in increasing adoption among the software development community.
As Anexinet's Vice President of Digital Solutions, Steve leads product and service innovation to help clients win by transforming IT from a cost center to a vital business asset and competitive differentiator. As a published author and featured speaker with a proven history of success in IT operations and business development, Steve has been a technology consulting leader for nearly three decades, and brings a business-outcome focus to the application of leading-edge technology aimed at improving the customer experience.