I'm new to iOS programming and being the organizational freak that I am, I'd like to have a good clean structure for everything I am working on.
Here's my current layout:
This project is open source: https://github.com/kirkouimet/enzyme
It's really up to you. It's sort of subjective, but usually Xcode's project templates provide a good start. Generally, I prefer Groups over literal folder references with the exception of the first couple of root-level directories.
Here's the typical file-system structure for my projects:
And here's what my Xcode project structure typically looks like: