Objective-C can look pretty intimidating if you are coming from AppleScript or even a language like Ruby. The funny thing is, once you use it for awhile, you really start to like the way the language is put together. Reading and maintaining your code requires much fewer comments because the language lends itself to being, well, self commenting. These are just a few of the many resources available for learning Objective-C but they will get you started. I suggest you watch the videos, read Daniel's book and then read Aaron's book. Daniel goes into a little more detail for the beginner.

Objective-C and Xcode Essential Training
I put together a video series for VTC.com covering Objective-C and Xcode.

Coding in Objective-C 2.0
Bill Dudney has created some very good beginner videos for learning Objective-C. There are three videos and they cost only $5.00 each. This is a steal and a tremendous benefit to those just getting started in Objective-C.

Becoming Productive in Xcode by Mike Clark.
Mike covers everything you every wanted to know about using Xcode from shortcuts to customizing code snippets and templates. Again, these are only $5.00 each.

Books Cocoa Programming for Mac OS X Third Edition by Aaron Hillegass.
This book is pretty much the holy grail of Objective-C books.

Cocoa Programming: A Quick-Start Guide for Developers by Daniel H Steinberg
This is an excellent book!