I think it makes sense. It is something that made it a bit easier to find things, though Xcode does give you that pulldown menu where you can search for stuff and there are autocomplete plugins for Xcode (though I wouldn't want to require that plugin in order to use a library). I did try to start the method with listXXX, but I couldn't figure out what I wanted to call the rest of the method.

- listAddToList:venueWithId:
- listAddTo:venueWithId:
- listAddVenueId:toListWithId
- listAddVenueToListWithId:venueWithId

None of them seem great. I'll pick one though (I'm leaning towards the last one honestly).