I am starting to get into iPhone development, and I find it very hard to get documentation.
Where can I find a complete API, tutorials, forums and so on?
I know that apple released some tutorials, are they helpful?
Is there some kind of "iPhone dev 101" post somewhere that I should absolutely read?
Anything will help.
You can check out AppsAmuck for some sample code:
Also, "Beginning iPhone Development" is a great book for beginners.
As far as the API and documentation of what methods are available... the developer docs are built into XCode, and were included when you downloaded the iPhone SDK.
If you are coming from another environment, you may be inclined to discount the Apple-supplied SDK documentation. Don't. It's actually quite useful, especially when used with the "Research Assistant" feature (which is context sensitive).
The Apple tutorials are not bad at all, but they do assume some familiarity with Cocoa (overall) when introducing a specific feature. If you don't have that base knowledge yet, they can be quite intimidating.
Stanford offers their iPhone Application Programming course for free online
The Apple docs are great, but I didn't find them terribly helpful when just starting out, because they tended to gloss over the initial creation of the app, or provided you a template without explanation.
One thing that's helped me a lot is Pragmatic Programmer's "iPhone SDK Development", available from http://www.pragprog.com/titles/amiphd/iphone-sdk-development . The book is currently in Beta, which means if you buy it, you get periodic revisions in PDF form. They've put off publishing the book until the iPhone 3.0 code goes public, but they're rewriting parts of the book to use the new APIs in favor of the ones that 3.0 deprecates.
It has a LOT of concrete examples and doesn't assume any great familiarity with Cocoa (or even C). Plus, it talks you through all the basics of getting the App up and functional from scratch, so you know why you're using one kind of a controller over another, and why all the various properties are set the way they are.