Version Compatibility

This book describes Swift 5.5, the default version of Swift that’s included in Xcode 13. You can use Xcode 13 to build targets that are written in either Swift 5.5, Swift 4.2, or Swift 4.

A target written in Swift 5.5 can depend on a target that’s written in Swift 4.2 or Swift 4, and vice versa. This means, if you have a large project that’s divided into multiple frameworks, you can migrate your code from Swift 4 to Swift 5.5 one framework at a time.