No video feed on the iOS device

If the Unity app loads but the screen is blank, that could be due to a number of causes. Double-check to see that you've granted permissions to use the camera by filling in Camera Usage Description.

With ARToolkit, users have also reported that you should enable Allow non-RGB video internally in the AR Controller component (and try disabling Use native GL texturing):

For other errors, Google is your friend.

Get Augmented Reality for Developers now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.