Workflow for new Xcode Project files

[ckib16]

There seems to be no workflow described in the text for how to "re-use" your text as you progress among the different program examples.  Several other posts in the forum ask this same question, but none have been answered well.  

Example: I've started a new Xcode project and typed in the code from book example "A".  I'm now moving on in the chapter and want to incorporate the small code changes shown in book example "B". However, I want to keep a copy of  "A" exactly as written for future reference.

 Do I:
1) "Duplicate" the Xcode project.  My google search seemed to point to no way to duplicate Xcode projects
2) overwrite parts of program A with changes in program B and use a "save as" function to save it as a new project?
3) If you can't duplicate or "save as", is the default workflow for each new variation/exercise to:
- File / New Project
- create new class files as needed (.h & .m)
- manually copy/paste code into each file
- save project

Am I missing something?  What is the preferred Xcode code workflow?