You can even complete functions from the standard library in cc65 based projects and jump to those function definitions in the headers. Under the 'Cross-platform' tab, you will see an 'Apple II' section with the different project types. So, to start a new Apple II project in Xcode, select File->New->Project.
That way, you can modify the hardware configuration to be exactly the config you want to test under. Also, it uses a hardware configuration which is stored in the make directory in your project. It also works with Applesoft and Merlin32 based projects. This works for all supported Apple configurations with cc65 based projects. This project was built based on the one created by Quinn Dunki but it has been expanded to add the following features: A build pipeline for making 8-bit Apple II software on OS X using cc65, Applesoft BASIC or Merlin32.