I spent a few hours last night porting my Grand Central Dispatch wrapper GCDObjC to Swift. Although Craig Federighi described it as "Objective-C without the baggage of C," the C bindings seem to be really straightforward. In Xcode, Autocomplete and Quick Help both show the GCD API calls translated into Swift:

The only thing I found unclear was how to call OSAtomicIncrement32(), which expects a pointer to a non-const 32-bit integer, but digging around in the well-commented header files helped.