The release of Swift 3 is quickly approaching, bringing many welcome changes to the language. Unfortunately Swift 3 is not backwards compatible with Swift 2 code - most projects will require changes to be ready for Swift 3.

Wouldn't it be nice to know how Swift 3 will affect your project - today?

You can. Here is how.

Getting the Tools

The first step is to download a build of Swift 3. Go to the Swift downloads page and download a recent preview release for Xcode.

Swift snapshot and preview releases for Xcode are distributed as package installers. Open the package that was downloaded and install it on your Mac.

Once the package is installed open Xcode. In the "Xcode" menu at the upper left of the screen there is a sub menu titled “Toolchains”. This allows you to easy switch between the default Xcode support for Swift 2.2 and the preview release you just installed. Once you change toolchains Xcode will need to quit and reopen. Select the preview release toolchain and allow Xcode to quit.

Discovering Swift 3 Issues

Now you can build your project with Swift 3. Open your project, clean it and build it. Even a trivial project will have some issues - the Issues navigator in Xcode will list them all once the build is completed.

You can switch back to Swift 2.2 at any time using the Toolchain menu.

With that list of issues you can now plan the work that will be required to transition to Swift 3. The information that Xcode provides should be enough to create engineering estimates for the work that will have to be performed to prepare your project for the release of Swift 3.