Harry Potter star Daniel Radcliffe has started perfecting his signature after learning he's the king of a new red carpet trend - iPhone autograph hunters. The British teenager reveals fans have started asking him to scratch his signature onto the back of their iPhones. He says, "The thing I've been signing recently is iPhones. I've signed about half a dozen of them. People at the red carpets present them to me. "I'm like, 'Are you sure? This is an expensive phone and my writing is horrible.'"