It took me a while and I've seen other people struggle with connecting the Tascam Portacapture X8 to an iPhone to do recording. In this video I will show you how to hook it up for a few different use cases. Hopefully this will help some other folks having the same issues!
Here are links to the components needed:
iRig - https://amzn.to/47Tu9H6
USB C to microphone adapter - https://amzn.to/3vOdkQF
Guitar to headphone adapter - https://amzn.to/4bbgkH0