In general, Vim on an iPhone (via iSH, a-Shell, or iVim) works surprisingly well. I thought the idea was ridiculous until I gave it a proper try (even though I was already a Vim user on “real” computers), since it doesn’t really leverage the touch interface for e.g. cursor movement and scrolling.

However, Vim’s design gives you maximum expressive power per key you press - and since pressing each key on an iOS keyboard is a bit inconvenient, this design philosophy ends up working really well on a soft keyboard. Moreover, most common actions can be done without special keys (i.e. arrow keys, ctrl/meta modifiers, etc.) which I usually find awkward to use on augmented mobile keyboards. With Vim, you can get quite far using just a standard iOS with an added Esc key (all of the apps I mentioned above adds an Esc key).

If you use Vim on desktop/laptop but haven’t tried it on iOS, I’d recommend giving it an hour of trial sometime, at least if you sometimes want to edit code on the go. (Personally, I rarely do that, but I like that I can.)