Unity 3D tool has features such as visual editor, multi-platform game build support, full and robust scripting and animation system to provide robust development for high-quality games and apps. Unity3D is a powerful cross-platform 3D engine and a user friendly development environment. Easy enough for the beginner and powerful enough for the expert.
Prime31 are a series of pluggins that let you implement the Unity programme into your iOSapplications. Prime 31 is well documented and requires you having Xcode closed the first time you build your project. It is required you do a Build (not a Build and Run) or your Xcode project may not get setup properly.