Swiftify does not include a converter between different Swift versions because such a converter exists in Xcode.
To migrate to a newer version from Xcode, choose Edit -> Convert -> To Current Swift Syntax from the Xcode menu.
Depending on your source code's Swift version, you might need a different Xcode version for the conversion. To get an earlier version of Xcode, you can use your Apple Developer Account to download it from the Apple Developer Portal:
- Swift 1 -> 2, Xcode 7
- Swift 2 -> 3, Xcode 8
- Swift 3 -> 4, Xcode 9
- Swift 3 or 4 -> 4.2, Xcode 10
- Swift 4 or 4.2 -> 5, Xcode 10.2.1
For more information on migrating to Swift 5, check Swift’s official blog where you can also find migration guides for earlier versions of Swift.