Xcode 9 includes a brand new refactoring engine. It can transform code locally within a single Swift source file, or globally, such as renaming a method or property that occurs in multiple files and even different languages. The logic behind local refactorings is implemented entirely in the compiler and SourceKit, and is now open source in the swift repository. Therefore, any Swift enthusiast can contribute refactoring actions to the language. This post discusses how a simple refactoring can be implemented and surfaced in Xcode.