iPhones were a type of mobile phone on 21st century Earth. Patricia Menzies mentioned iPhones to the Sixth Doctor. (AUDIO: The Crimes of Thomas Brewster)
Courtney Woods had an iPhone, and she used it to post pictures of the Twelfth Doctor on the Moon onto Tumblr in the year 2049. Clara Oswald noted that to the Doctor. Even though he said she couldn't just put pictures of him online he was later able to use the online pictures via her phone to lead her back to him in the TARDIS. (TV: Kill the Moon)
Other similarly named devices from that era included the iPad and the iPod. (TV: Dark Water, A Day in the Death)