With an iPhone, it’s easy to watch UltraViolet movies and TV shows, either by streaming or downloading the content. Since all iPhone’s are the same (except for a larger screen on the iPhone 5, iPhone 5S & iPhone 5C), this tutorial should work for you regardless of the generation of iPhone you have.
However, there isn’t an app called “UltraViolet”. Instead need to download an application from the App Store called “Movies by Flixster”. By downloading and installing the Flixster app on your iPhone, you’ll have direct access to your cloud-based UltraViolet account from anywhere in the world (subject to Wi-Fi / 3G / 4G coverage).