Pages from the SDK-101 Course:

SDK-101
Resources

Available from Amazon.com:
Programming in Objective-C 2.0

This is an excellent book from which to learn Objective C and to use as a reference.

Available from Amazon.com:
iPhone SDK

I love O'Reilly books -- I find them concise and practical.

iPhone Dev Center

This is your home page for developing iPhone and iPod Touch applications, and the place from which you can access a huge variety of useful resources and the iPhone Developer Program portal.

Available from iPhone DevCenter:
The Objective-C 2.0 Programming Language

This is Apple's Guide to Objective-C. It is an excellent reference and you can also download the PDF for it.

Available from iPhone DevCenter:
Cocoa Fundamentals Guide

This is Apple's Guide to Cocoa Fundamentals. It is a valuable resource for anyone who is new to programming in the Mac and iPhone environment. You can also download the PDF for this document.

Available from iPhone DevCenter:
iPhone Application Programming Guide

This is Apple's Guide to writing applications for the iPhone. It is a must-read for anyone who wants to become an iPhone programmer. You can also download the PDF for this document.

iTunes Connect

This is where you submit your applicaiton to Apple for inclusion in the App Store.