Are there any good books on using Grand Central Dispatch? I've found: Concurrent Programming in Mac OS X and iOS but I wanted to know what books people recommend. I'm not a programming expert and I'm looking to learn how to properly implement concurrency. For example, I want to do any importing or parsing on a separate thread, but be able to stop the parsing process if the user selects a different file. That way there isn't a big lag between selections. I've gone through the Concurrency Programming Guide and read some posts on cimgf.com, but I still feel a little lost and could use the step-by-step explanations found in a book dedicated to the topic.