I know this is beginners book and also perhaps the reason authors haven’t introduced it (yet! i am on chapter 11) but instead of copying the application for your challenges, you can use xcode’s git source control, you don’t have to learn command line or any advance stuff but little bit about commits and branches. You will have to learn it eventually
Here is how I do it:
- Start the project with Git source control
- Write the chapter code in master branch
- Start new branch for each Bronze, Silver and Gold challenges
- Switch to master for new chapter
Hope this helps!