Right now its a simple .c file but to finish the project I need to make .h and .cpp files and would like to test run them on my mac but i dont know how, just how to compile them.

The often overlooked Xcode FileMerge app lets you spot what's changed between two files. Here's how to spot the differences using the tool.

Apple has a twenty-seven-minute video from WWDC '23 called "Build programmatic UI with Xcode Previews" which summarizes how to use Xcode Previews to see your UI as you build it.