Against Apple Terms I believe. They will ban you if they find out.
I was talking with apple support and they basically said that if we even offered some extra component to get rid of the spinning gear we would most likely be banned.
Citation of the specific term needed. It isn’t against any of them and plenty of apps do it (Things, Boom or Monity come to mind). Apple requires that the app is functional without extra downloads and the app itself must not download the extra executables. But it’s OK to use them for extended functionality (Things: system-wide popup; Monity: extra sensors) as long as you only point the user to where to download the extra helper and they do it themselves (see e.g. http://www.monityapp.com/helper/ for one such helper download page, linked from in app).
I was talking with apple support and they basically said that if we even offered some extra component to get rid of the spinning gear we would most likely be banned.