Today I’d like to recommend a great tutorial from Derek Selander on Grand Central Dispatch on Ray Wenderlich @ http://www.raywenderlich.com/60749/grand-central-dispatch-in-depth-part-1. Derek is an iOS developer currently working in the mobile health sector. You can find Derek on Twitter or LinkedIn. This tutorial is a two part series and you’ll find the link to the second part of the tutorial on the page. Grand Central Dispatch (GCD) is the marketing name for libdispatch, Apple’s library that provides support for concurrent code execution on multicore hardware on iOS and OS X. GCD helps to improve the responsiveness of applications by deferring computationally expensive tasks to the background, it provides an easier concurrency model than locks and threads, helps to avoid concurrency bugs and potentially optimise your code with higher performance primitives for common design patterns such as singletons. For this tutorial on http://www.raywenderlich.com it is assumed that you would have basic knowledge of blocks. If however you don’t, you can check out the Video Tutorial for Blocks also on http://www.raywenderlich.com which is available for subscribers, Ry’s tutorial @ http://rypress.com/tutorials/objective-c/blocks.html as well as AppCoda’s tutorial @ http://www.appcoda.com/objective-c-blocks-tutorial/.