I'm supposing that he naturally made the project appstore ready because he knew what the requirements for that were, as in he did not write what he needed and then fixed it, he instead did not write anything that went out of guidelines.

As far as the other stuff, this reminds me of recruiters who send you a coding project that they say will take 2-3 hours that generally takes 4-6 if there isn't some major problem. The extra time is of course setting everything up choosing what dependencies you need etc, because every project is slightly different and you are unlikely to have everything that is needed for that one project. The actual coding is probably 2-3 hours.

So perhaps he already had everything his system needed, if so I expect it might have taken 1 hour to code (because he was very comfortable and knew exactly what he would need to do) and some minutes to make git repo, push code. Then add another hour to time compiling and submitting to app store.

If he knew what he needed to do in the code of course that was probably from thinking about it for weeks beforehand.