This is just a wild hunch, but you might be able to use Mathematica's Mail functions to send an email to your iPad. The email might contain some distinguishing keyword. Apple now has a scripting tool in iOS called Shortcuts. It may be feasible to write a Shortcut that you would start and leave running, which would read your incoming mail, detect your keyword, take a photo, then email it back. Mathematica can read emails, so could detect a keyword, and import the image. This could be probably be packaged up very nicely into a single routine and would work at long distance if your iPad had cellular service. If SendMail would work on my Mac, I would test this, but it has not worked for me since Version 10. The MailServerConnect routines for reading mail, however, work fine on my Mac.