I have an iPhone 5s. My dad also has an iPhone 5s. We are trying to share photos. Airdrop won't recognize him on my iPhone or me on his iPhone. We've tried setting Airdrop to "contacts" and to "everyone" with no success. He's used Airdrop on his iPhone with someone else and it worked. This is my first time trying to use it. Has anyone else had this issue? Can anyone help?