Learning Classes and Methods

Hi, I'm learning Objective-C. I've quickly realized that my success as a programmer in Objective-C will be directly proportional to my understanding of the Classes and their Methods that are contained in the Foundation Framework. However, there are dozens and dozens of Classes and hundreds of not thousands of Methods contained therein.

I know there are no shortcuts to becoming a successful programmer, but there are better ways than others to do certain things, so my question is - what is the best way to learn which classes are available in the Foundation Framework and which Methods each of those Classes offers?

In other words, do I simply read through Apples documentation for these tools, should I purchase an O'Reilly book that may list them out in a simple dictionary fashion, should I use the online code assistance as I move though my different example, is there an online website that would be more effective or efficient, etc.

Again, I'm not asking for a shortcut, so that I don't have to put forth the effort, I'm asking for a "best approach" way to learning an huge amount of tools.

Thanks for your help,
Fulano