Three teenage bag snatchers are a lot wiser about iPhones after being tracked down by a GPS app. The trio, aged 13, 14 and 15, rode up on pushbikes and stole a handbag off a 27-year-old woman as she walked with a friend in Cairns at midnight on Friday. After chasing but failing to catch the teenagers, the women went to the police, who tracked the phone by activating its \"find my phone\" app. The app uses GPS technology to pinpoint the position of a device on which it is loaded. Police tracked the phone to a Cairns address and retrieved the phone and three stolen pushbikes. The teenagers are being dealt with under the Youth Justices Act.