NuclearVision wrotei heard apple is working on a new language called swift.
You might want to look into it. It has easier syntax than obj-C. And might be the future of apple programming.
Yes the Swift syntax is easier, especially in complex code such as blocks/closures/lambdas. However, the fundamentals of programming in iOS remain: learning the Cocoa API is relevant whatever the language you use, so the book mentioned above is certainly very useful. One has to learn the standard iOS programming patterns as well as how to use the core libraries.
Also note that any app coded in Swift today will automatically include the Swift runtime as a static library, adding around 8.5MB of code to your app. Not a big deal, but worth mentioning.