In responding to another topic, I spotted your questions @jsamlarose. I do have code completion running in an iOS editor. Here’s a screenshot of me entering a property of draft in an alert(), and it listing content as I type in the text.
You may note that the look and feel of what I’m using is very similar to my VS Code set up above. That’s because it is, and it uses the same configuration files, etc. 
The app I’m using has a terribly generic name in the app store of “Code”, so here’s the app store link because otherwise it is a pain to find.
You can read about the app here:
I’ve been using it for maybe 7 or 8 months now I think and while I don’t do a lot of editing on it, when I do it has been great.
Hope that’s useful.