Apple is helping to promote Hulu's Castle Rock in a surprising way: By offering the premiere episode free on the Apple TV app. It'll be available to iPhone, iPad and Apple TV users in the US later today, and it'll be there exclusively for two weeks. It's a smart move for both Apple and Hulu. Castle Rock -- based on Stephen King's rich universe of stories -- is one of the most anticipated series this summer, and early reviews have been incredibly positive. By offering the first episode for free, Apple can get more people to pay attention to its TV app, while also encouraging viewers to pick up a Hulu subscription to keep watching.