Semen,
To my limited knowledge so any correction is welcome:
The trouble with iOS photos is they are stored in the photo album, by default, in HEIC format - the user can change this to jpg but this is not within the reach of my (or any other?) app.
The problem with HEIC is that it has proved to be a format with limited adoption by others - and you don't know what format/s the app you are sharing with will accept. Or more correctly you can limit the range of apps you can share to by specifying (say) jpg.
Also, if I wanted to restore the photo to jpg I have an additional problem - what was the original jpg compression?
To avoid these sorts of issues I decided to share photos as bitmaps - the lowest common denominator.
An interception of console messages is not a simple task.
I appreciate your time and effort here - I can live without knowing precisely why a share attempt failed.
My workaround involves a mechanism so that when a share failure is detected the user is given a dialog:
He can then reduce by 10%/20%/... and retry or quit.
The only problem with this is that it will be triggered by either the user cancelling the share OR the share failing (and generating the notorious log message).
If it is generated because the user cancelled the share then it is a bit clunky.
Thanks again...