I’m not really sure what the state of ARKit learning materials is but there are great tutorials online by e.g., Ray Wenderlich. Getting started with Xcode and iOS can be a bit of a struggle. Follow some tutorials and take it step by step. Apple has some pretty good samples, too.

Unfortunately one big problem is the quality of Apple’s documentation. It’s nowhere near as good as e.g., the Unity engine documentation or Microsoft’s API docs. At best, it’s useful for discovering what exists and then you either figure it out or look for specific examples online.