Complete guide to Swift 3.0 and its new features

What new features did Apple add to Swift 3.0 at WWDC 2016?

Swift 3.0 is the latest iteration of Apple’s programming language. The new features for Swift were unveiled during Apple’s WWDC 2016 (Worldwide Developers’ Conference) on 13 June 2016.

Following Apple’s WWDC announcement, Swift 3.0 was made available to developers. The Swift 3.0 Preview 1 is available as part of Apple’s Xcode 8.0 beta. The good news is that anybody can get hold of Xcode 8.0 Beta, and it’s not locked to developers with a paid Apple Developer Program account (unlike the early betas of iOS or OS X).

In this article, our complete guide to Swift and Swift 3.0 in particular, we look at all the new features and explain everything you need to know about Apple’s Swift programming language.

Complete guide to Swift 3.0: New features

The Swift Programming Language (Swift 3 beta) book outlines most of the new features implemented in Swift. Near the end of the book is the Document Revision History, which serves as a great guide to the new features implemented in Swift 3.0.

Here are some new features implemented in Swift 3.0 documented in the revision history:

All function parameters have labels by default.
Attribute arguments use a colon.
Swiftch cases with multiple patterns have new functionality.
Line control statements use the #sourceLocation(file:line) syntax.

Nonescaping Closures and Autoclosures are now type attributes rather than declaration attributes.

Parentheses are now required around the parameter types in functions.

You can discover more about the new features in Swift 3.0 by reading The Swift Programming Language (Swift 3 beta) or by heading over to Swift.org’s Migration Guide.

Porting to Windows and Linux

Swift 3.0 at WWDC 2016

One major implementation that we’re going to see with Swift 3.0 is the porting of Swift to other operating systems. According to Apple’s Swift Evolution GitHub page, the Swift team intends to “make Swift available on other platforms and ensure that one can write portable Swift code that works properly on all of those platforms.”

That Swift is heading to Linux, and perhaps even Windows, is no secret. As soon as Apple made Swift open-source the potential was there to port it to other operating systems.

Craig Federighi, Apple’s Senior Vice President of Software Engineering, said: “We’re certainly open to the community creating a Windows port, and there’s a good foundation for that in that the LLVM and Clang environments that are foundations for building and compiling Swift have been ported to Windows. We fully support the community doing that port. Regarding us getting the [open-source] project off the ground, we wanted to focus our energy on our platforms and Linux to start.”

It certainly seems that taking Swift to other platforms is going to be part of WWDC: Linux for sure and Windows possibly. Microsoft, for its part, has brought Ubuntu Linux inside Windows 10, so we’re seeing some convergence for developers on all platforms.

Again, we should note that features Swift on Linux or Windows is not the same as having Xcode and the Apple SDK (software development kits) available. You won’t be able to developer OS X (or “macOS” as it’s rumoured to be renamed at WWDC 2016) and iOS apps.

Swift 3.0’s new features: Welcoming Google to the fray

Meanwhile, we’ve heard rumours that Google is preparing to drop its Java-based programming language for Android in favour of Swift (in part to sidestep increasing legal problems Google is having with Oracle, the owners of Java).

This would be a bold step, and while it seems odd for fierce rivals like Google and Apple to share a base language, it’d be a move welcomed by developers. Swift is the “most loved” programming language, according to StackOverflow’s 2015 survey. It makes sense in a lot of ways for Apple and Google to focus on promoting one underlying coding language and then work to develop their strengths inside that.

Whether Google joins the Swift party is up to them, but we’ll probably find out one way or the other at WWDC 2016.

Swift 3.0 at WWDC 2016: New features

Looking at the release notes for Swift 3.0, we can also see some things that the Swift team is looking at. Here are some highlights:

Stabilize the binary interface (ABI). The Swift team is looking to create a more stable ABI allowing Swift to interact with different types of computers (at the binary level). Again, this points to Swift being ported to different computers.
Complete generics. Swift uses generics (algorithms that are instatiated when needed) throughout its libraries, and Swift 3.0 will fully complete the implementation.
Type system cleanup and documentation. Swift 3.0 will “Revisit and document the various subtyping and conversion rules in the type system, as well as their implementation in the compiler’s type checker.”
Focus and refine the language. There’s little detail here as to how, but the Evoltuion Document notes that: “Swift’s rapid development has meant that it has accumulated some language features and library APIs that don’t fit well with the language as a whole. Swift 3 will remove or improve those features to provide better overall consistency for Swift.”
API Guidelines. Swift 3.0 provides new design guidelines for developers building APIs.

An out-of-scope section details what Swift 3.0 won’t be doing in the future; in particular, it won’t be expanding out to C++ Interoperability, so C++ programmers won’t be able to integrate their code in the same way as Objective-C designers.

According to the document: “APIs. Interoperability with C++ libraries would enhance Swift’s ability to work with existing libraries and APIs. However, C++ itself is a very complex language, and providing good interoperability with C++ is a significant undertaking that is out of scope for Swift 3.0.”

Complete guide to Swift 3.0: How to download and install Xcode 8 beta

Installing the Xcode 8 beta

To experiment with the new features found in Swift 3.0, you’ll need to download and install the Xcode 8 IDE (Integrated Developer Environment). Here is how to install the Xcode 8 beta on your Mac:

Open Safari and visit developer.apple.com.
Click Account and enter your Apple ID and password. Click Sign In.
Select “By checking this box I confirm that I have read and agree to be bound by the Agreement above. I also confirm that I am of the legal age of majority in the jurisdiction in which I reside (at least 18 years of age in many countries)” and click Submit.
Click Download Tools.
Click Download Xcode 8 beta. The file will be saved to your Downloads folder.
Double-click the Xcode_8_beta.xip file. Xip files are like zip files, but they are integrity checked against a checksum before expanding. It took around five minutes for us to expand the file.
Drag the Xcode-beta file to the Applications folder. Double-click it to open. OS X will again verify the file before opening it. Click Open when the check has finished.
Click Agree in the Xcode and iOS SDK License Agreement window.
Enter your Admin password and click OK. (If an alert appears stating that programs like Xcode and iTunes must be quit first; click Quit All).

Now that you have Xcode 8 installed, you can start to try out Swift 3 programming and features. Click Get Started With a Playground or Create a New Xcode Project.

Complete guide to Swift 3.0: The Swift Programming Language book

The Swift 3 programming language

The last word on reference for Swift is Apple’s The Swift Programming Language book. The latest version, The Swift Programming Language (Swift 3 beta) is available on the iBooks Store. Alternatively you can download an ePub of The Swift Programming Language from the swift.org website.