Save yourself, be happy, get plenty of exercise, eat your veggies, and when jumping into the 3D graphics pool, especially for the first time, for the love of all you hold near and dear to your heart start, with SceneKit. Also, get warm and fuzzy with GLKit, specifically its vectors, matrices, and GLKQuaternion.
Why GLKQuaternion, and SceneKit's SCNQuaternion? Well, let's talk about how to handle cameras, which are as important to a good 3D app as an aged Reposado tequila is to a Margarita. I'll distill it down to a word–Quaternions. They may look scary but when you are moving all around they are your big 'ol friend who just happens to show up as you're about to be mugged in a dark and dangerous alley by Gimbal Lock and his friends from the Euler family. The first time you're twisting a camera all which ways, you'll thank me. I say this to to you now because I wish someone had said this to me 12 years ago when I picked-up the monkey on my back that is 3D graphics–how I love the eye candy!–but was mugged...several times. Never said I was smart.
If in some hopefully very distant future you have an epiphany that you need to get closer to the silicon, well then, there's Metal. By that time, Metal will be less of a leap for you than it would be now.
¡adiós!
