Recently I discovered an iOS ebook-reader called “MARVIN” which can by using an url-scheme easily export marked text while reading.
The app has in its setting a section ebook-setting and then text selection menu - and the following scheme works flawless:
anki://x-callback-url/addnote?profile=NAMEOFPROFILE&type=NAMEOFNOTETYPE&deck=NAMEOFDECK&fldNAMEOFFIELD={text}&x-success=marvin3://