As a user it can be extremely frustrating if you’re using an application and you have to wait an extended period of time while the application updates.
Sadly this was pretty common when the app store was new. The devices were slower, the networks were slower, and many apps weren’t using multi-threading in places they probably should have. I remember becoming frustrated many times using an RSS reader, waiting for the article list to update, and then waiting again for the article to display.
Thankfully Apple introduced Grand Central Dispatch (GCD) with iOS 4.0.
Multithreaded programming with GCD can still be intimidating. I’ve found a great step-by-step guide which breaks things down into a step by step guide explaining things fully every step of the process of downloading data asynchronously and updating in real time.
The tutorial is from Ray Wenderlich, the creator of the Space Game Starter Kit and co-author of the Learning Cocos2D book, And Can Be Found Here:
Multithreading And Grand Central Dispatch On iOS For Beginners Tutorial
An excellent example of a tutorial that makes a complicated subject seem so simple.