I honestly wouldn't copy an existing project. You need to change so many things that it's easier to just start a new project and copy over any code or assets you want to re-use.
it's also a great opportunity to re-structure and refactor your project to make it more modern or maintainable.
I recently tried to create a new app from an existing one as they shared similar code and structure, but I ended up trashing it because I kept getting errors that files didn't exist, etc.
Topic:
Developer Tools & Services
SubTopic:
Xcode
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