Bitten by a global queue

Just a quick note to remind myself and anyone else who might be getting a EXC_BAD_ACCESS when using dispatch_get_global_queue, Xcode 6 and iOS 8.x SDK and testing on iOS 7.x devices:

Xcode 6 was nice enough to auto-complete my code to:

dispatch_get_global_queue(QOS_CLASS_BACKGROUND, NULL)

which will naturally return NULL when running under iOS 7.x, where the QOS_CLASS_X values don’t map to anything…