Jonathan, I checked the app store and cannot find an alternative.
Btw, the big problem with such apps is that iPhone / iPad cameras are typically no more than 53°. This is a big practical problem since most fixed lens IP cameras are between 70° and 120°, making an iPhone lens app not very useful.
Btw, you can use our various scenes (intersection, hallway, lobby, entrances, etc.) and FoV preview tool in our Camera Calculator to estimate / project any FoV from 1° to 180°.
We'd still like phones to be able to simulate in real time but until / unless phones support wide angle lenses, that will be a big limitation.
Give this one a gander. It's called setmycamera.
You have to dig a bit to find the cctv imagers, but they're in there. As for the 53 degree limitation, there are a whole mess of a magnetic wide-angle add-on kits for i-devices you could give a whirl, though i haven't the faintest idea on how to inform the software about your new angle.