Not an API, but still doable to a certain scale. I've gotten image input to work with my bot. Apple once temporarily banned me for suspicious activity but after a quick call to support they lifted it. If I got more traffic maybe they'd ban it again, I'm not sure.
You can text !help to sue [at] robertism.com to demo if you're interested.
You can text !help to sue [at] robertism.com to demo if you're interested.