Swift 3.0, the first major release of Swift given that it used to be open-sourced, is now officially released! Swift 3 is a large release containing essential improvements and refinements to the core language and Standard Library, principal additions to the Linux port of Swift, and the first stable release of the Swift Package Manager.
Swift 3 is a source-breaking release, mostly due to the modifications in SE-0005 and SE-0006. These changes now not only have an impact on the names of the Standard Library APIs, however also absolutely change how Objective-C APIs (particularly from Cocoa) import into Swift. Many of the adjustments are generally mechanical, but they can be numerous in a ordinary Swift project.
To help with shifting to Swift 3, XCode 8 incorporates a code migrator that can routinely handle many of the want source changes. There is additionally a migration guide handy to guide you thru many of the modifications — mainly via the ones that are much less mechanical and require extra direct scrutiny.