If you don't know it, I have recommended Epoccam dozens upon dozens of times in this forum as a way to get an iOS device's webcam into Isadora via Syphon on macOS. It was easy to use, reliable, and low latency.

I am disappointed to inform you that that Epoccam has been bought by Elgato, and they have just informed me in an email that they will no longer support Epoccam Viewer Pro -- the app that allowed up to four iOS devices to provide a Syphon feed into Isadora and any other application that supports Syphon. Instead they are now supporting only a virtual web cam input. As a video developer, I can only surmise that such a system will have a much higher performance impact than using Syphon. 

Because of this, I can no longer recommend this software.

If you use Epocam and love it as I do, you are invite to write Elgato support and tell them they are making a mistake.

That said, you should know that a copy of Epoccam purchased by a friend from the App Store last week still works with Epoccam Viewer Pro. I had to .zip my copy of Viewer Pro and send it to this person. So if you have a copy of Viewer Pro, you can still use it at the moment. Of course, that could all end if they update the iOS app.

Best Wishes,
Mark