Start with the standard stuff: Objective-C and UIKit. You don't need any frameworks beyond this unless you are building a game and there will be plenty of time to fight with other poeples code when you are adding ad networks, analytics, in app purchases and so on without adding frameworks into the mix.
Objective-C and UIKit are quite large (Just Google NSString and look at all the methods on this basic type) and you need to learn as much of the standard stuff as you can. It's going to take some time and a lot of effort to be able to crank out polished apps in weeks instead of months.
If you are planing on building games then I would still recommend starting with the basics. Make a UIKit based app first. Then try your hand at a simple 2d game with box2d and cocos2d. If you are going to do 3d don't go with Unity right out of the gate. Go make some "simple" stuff using OpenGL ES direcectly. Good luck!
Objective-C and UIKit are quite large (Just Google NSString and look at all the methods on this basic type) and you need to learn as much of the standard stuff as you can. It's going to take some time and a lot of effort to be able to crank out polished apps in weeks instead of months.
If you are planing on building games then I would still recommend starting with the basics. Make a UIKit based app first. Then try your hand at a simple 2d game with box2d and cocos2d. If you are going to do 3d don't go with Unity right out of the gate. Go make some "simple" stuff using OpenGL ES direcectly. Good luck!
PS. If you are ever in SF stop by our weekly iOS meetup: http://www.meetup.com/iphonedevsf/