Just imported a photo from an SD card, into my iPhone, via an SD card reader for iPhone. Sweet!
GoldFox SD Card Camera Reader for iPhone iPad [Upgraded] Trail Game Camera Card Viewer Reader for iPhone 6/6s/6s Plus/5/5s/7/7 Plus/iPad Mini/Air, No App Needed
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Image: Import screen
This is the screen you see on your iPhone when you insert the SD card into the reader.
Select the phones that you want to import, keep them on the card or delete them.
Then they are copied into your iPhone Camera Roll.
Image: Imported Photo