There are none. Any that you see on the AppStore aren't actually antivirus in the sense of what you'd get for an actual PC.
Of all the phones out there iOS is probably the least likely to ever get malware. Too complicated unless you downloaded something you shouldn't have in the first place.
Edit: Unless you got an app from the store that did something or got into your phone by other means Apple didn't intend to. For all intents and purposes iOS doesn't actually get malware of any sort. It's just how the systems built.
Have had iPhones for about 5 years now without any sort of malware issues beyond a webpage opening the App Store.