MAC:GCD
lastmod 2026-11-10created 2014-03-042 edits
GCD (Grand Central Dispatch) is a concurrency programming technology that Apple provides on macOS and iOS. Instead of creating threads directly, you put tasks (blocks or closures) on a dispatch queue, and the system runs them while managing a thread pool. It provides serial and concurrent queues, the main queue, groups, semaphores, dispatch sources, and more; it is implemented as the C library libdispatch and can be used from both Swift and Objective-C.