What Are Blocks In Objective-C?

If you take a look at the new documentation (since iOS 4) you’ll find some strange notation for some of the API.  For instance, if you look at the API for NSArray you’ll find some methods like this: – (void)enumerateObjectsUsingBlock:(void (^)(id obj, NSUInteger idx, BOOL *stop))block;   Even if you’ve been working with Objective-C for [...]