How to Update Xcode for a New Swift Release
New releases of Xcode (downloadable from developer.apple.com for the beta and pre-release versions and from the Mac App Store for released versions) include documentation and APIs for new versions of Swift and the Cocoa and Cocoa Touch APIs. If you need to load older versions, go to the Downloads tab at Xcode→Preferences to review what needs to be downloaded. The unchecked items are available for download. The checked items have already been downloaded.