I\'ve looked through the site to make sure this isn\'t a duplicate. Apologies if I\'ve missed something.
I\'ve been doing iPhone development for about a year now, an
Thankfully, Cocoa on the desktop and Cocoa Touch are very similar. I would recommend just downloading some beginner sample code from Apple's website. Since you already know Objective-C/Cocoa, you should be able to follow along pretty easily. If some parts are confusing, you can skim through Apple's guides.
Things that are the same:
Things that are different:
Edit: Overall, the main different the iPhone has more 'pre-built' UI classes (UINavigationController, UITabBarController, etc.) you can use in your app to make it look nice and pretty (and most importantly, consistent with Apple apps).