You'll have to go into your settings to trust non-App Store apps on an iPhone. Here's how to make your iPhone trust these ...

You can download apps on your Apple TV device using the Apple App Store, and customize your Apple TV home screen.

Sideload apps: Follow developer instructions to add to your phone. Not common. Risky: Jailbreak an iOS device and load apps to it. This article explains how to get apps that are not in the App Store ...