Comment by jraph

Mentioning it just in case, but openstreetmap.org's web editor (iD) is a good start on Desktop.

There's also EveryDoor [1] which is very nice to edit OSM and they do seem to have an iOS version. Depending on what you want to edit, it can be very handy.

I have not tried the numerous other, more advanced options [2].

[1] https://every-door.app/

[2] https://wiki.openstreetmap.org/wiki/Editors