Question: how to transfer photos from iphone to iphone via airdrop?
Answer: Tap a photo, album, event, journal, or slideshow and tap. > AirDrop.
Tap Selected, or change the photos you want to share (if you're sending a slideshow, skip to step 3): ... 
Tap the device name you want to send the items to.
On the iOS device receiving the items, tap Accept.