Sorry for the confusion, at the moment our iOS apps don't
support attachments, and while we do hope to add these with a
future update I can't promise when this may be.
For my own ETSA confirmation details I just added the
confirmation number and date, which I was told was all I'd need, to
the notes field of my Passport item. In reality, I've never been
asked for those details by any US immigration official on many
trips to the US.