# Dispatch Constants ## Topics ### Constants [`var DISPATCH_API_VERSION: Int32`](/documentation/Dispatch/DISPATCH_API_VERSION) [`var DISPATCH_APPLY_AUTO_AVAILABLE: Int32`](/documentation/Dispatch/DISPATCH_APPLY_AUTO_AVAILABLE) [`var DISPATCH_ONCE_INLINE_FASTPATH: Int32`](/documentation/Dispatch/DISPATCH_ONCE_INLINE_FASTPATH) [`var DISPATCH_SWIFT3_OVERLAY: Int32`](/documentation/Dispatch/DISPATCH_SWIFT3_OVERLAY) [`var MSEC_PER_SEC: UInt64`](/documentation/Dispatch/MSEC_PER_SEC) ### Macros [`#define DISPATCH_ALIAS_V2(sym)`](/documentation/Dispatch/DISPATCH_ALIAS_V2) [`#define DISPATCH_ALWAYS_INLINE`](/documentation/Dispatch/DISPATCH_ALWAYS_INLINE) [`var DISPATCH_API_VERSION: Int32`](/documentation/Dispatch/DISPATCH_API_VERSION) [`var DISPATCH_APPLY_AUTO_AVAILABLE: Int32`](/documentation/Dispatch/DISPATCH_APPLY_AUTO_AVAILABLE) [`#define DISPATCH_APPLY_QUEUE_ARG_NULLABILITY`](/documentation/Dispatch/DISPATCH_APPLY_QUEUE_ARG_NULLABILITY) [`#define DISPATCH_ASSUME_ABI_SINGLE_BEGIN`](/documentation/Dispatch/DISPATCH_ASSUME_ABI_SINGLE_BEGIN) [`#define DISPATCH_ASSUME_ABI_SINGLE_END`](/documentation/Dispatch/DISPATCH_ASSUME_ABI_SINGLE_END) [`#define DISPATCH_ASSUME_NONNULL_BEGIN`](/documentation/Dispatch/DISPATCH_ASSUME_NONNULL_BEGIN) [`#define DISPATCH_ASSUME_NONNULL_END`](/documentation/Dispatch/DISPATCH_ASSUME_NONNULL_END) [`#define DISPATCH_COLD`](/documentation/Dispatch/DISPATCH_COLD) [`#define DISPATCH_COMPILER_CAN_ASSUME(expr)`](/documentation/Dispatch/DISPATCH_COMPILER_CAN_ASSUME) [`#define DISPATCH_CONST`](/documentation/Dispatch/DISPATCH_CONST) [`#define DISPATCH_COUNTED_BY(X)`](/documentation/Dispatch/DISPATCH_COUNTED_BY) [`#define DISPATCH_DATA_DECL(name)`](/documentation/Dispatch/DISPATCH_DATA_DECL) [`#define DISPATCH_DATA_DECL_SWIFT(name, swift_name)`](/documentation/Dispatch/DISPATCH_DATA_DECL_SWIFT) [`#define DISPATCH_DATA_DESTRUCTOR_MUNMAP`](/documentation/Dispatch/DISPATCH_DATA_DESTRUCTOR_MUNMAP) [`#define DISPATCH_DATA_DESTRUCTOR_TYPE_DECL(name)`](/documentation/Dispatch/DISPATCH_DATA_DESTRUCTOR_TYPE_DECL) [`#define DISPATCH_DECL(name)`](/documentation/Dispatch/DISPATCH_DECL) [`#define DISPATCH_DECL_FACTORY_CLASS_SWIFT(name, swift_name)`](/documentation/Dispatch/DISPATCH_DECL_FACTORY_CLASS_SWIFT) [`#define DISPATCH_DECL_SERIAL_EXECUTOR_SWIFT(name, swift_name)`](/documentation/Dispatch/DISPATCH_DECL_SERIAL_EXECUTOR_SWIFT) [`#define DISPATCH_DECL_SUBCLASS(name, base)`](/documentation/Dispatch/DISPATCH_DECL_SUBCLASS) [`#define DISPATCH_DECL_SUBCLASS_SWIFT(name, base, swift_name)`](/documentation/Dispatch/DISPATCH_DECL_SUBCLASS_SWIFT) [`#define DISPATCH_DECL_SWIFT(name, swift_name)`](/documentation/Dispatch/DISPATCH_DECL_SWIFT) [`#define DISPATCH_ENUM(name, type, ...)`](/documentation/Dispatch/DISPATCH_ENUM) [`#define DISPATCH_ENUM_API_AVAILABLE(...)`](/documentation/Dispatch/DISPATCH_ENUM_API_AVAILABLE) [`#define DISPATCH_ENUM_API_DEPRECATED(...)`](/documentation/Dispatch/DISPATCH_ENUM_API_DEPRECATED) [`#define DISPATCH_ENUM_API_DEPRECATED_WITH_REPLACEMENT(...)`](/documentation/Dispatch/DISPATCH_ENUM_API_DEPRECATED_WITH_REPLACEMENT) [`#define DISPATCH_EXPECT(x, v)`](/documentation/Dispatch/DISPATCH_EXPECT) [`#define DISPATCH_EXPORT`](/documentation/Dispatch/DISPATCH_EXPORT) [`#define DISPATCH_FALLTHROUGH`](/documentation/Dispatch/DISPATCH_FALLTHROUGH) [`#define DISPATCH_FREEBSD_UNAVAILABLE()`](/documentation/Dispatch/DISPATCH_FREEBSD_UNAVAILABLE) [`#define DISPATCH_GLOBAL_OBJECT(type, object)`](/documentation/Dispatch/DISPATCH_GLOBAL_OBJECT) [`#define DISPATCH_INLINE`](/documentation/Dispatch/DISPATCH_INLINE) [`#define DISPATCH_LINUX_UNAVAILABLE()`](/documentation/Dispatch/DISPATCH_LINUX_UNAVAILABLE) [`#define DISPATCH_MALLOC`](/documentation/Dispatch/DISPATCH_MALLOC) [`#define DISPATCH_NOESCAPE`](/documentation/Dispatch/DISPATCH_NOESCAPE) [`#define DISPATCH_NONNULL1`](/documentation/Dispatch/DISPATCH_NONNULL1) [`#define DISPATCH_NONNULL2`](/documentation/Dispatch/DISPATCH_NONNULL2) [`#define DISPATCH_NONNULL3`](/documentation/Dispatch/DISPATCH_NONNULL3) [`#define DISPATCH_NONNULL4`](/documentation/Dispatch/DISPATCH_NONNULL4) [`#define DISPATCH_NONNULL5`](/documentation/Dispatch/DISPATCH_NONNULL5) [`#define DISPATCH_NONNULL6`](/documentation/Dispatch/DISPATCH_NONNULL6) [`#define DISPATCH_NONNULL7`](/documentation/Dispatch/DISPATCH_NONNULL7) [`#define DISPATCH_NONNULL_ALL`](/documentation/Dispatch/DISPATCH_NONNULL_ALL) [`#define DISPATCH_NORETURN`](/documentation/Dispatch/DISPATCH_NORETURN) [`#define DISPATCH_NOTHROW`](/documentation/Dispatch/DISPATCH_NOTHROW) [`#define DISPATCH_NOT_TAIL_CALLED`](/documentation/Dispatch/DISPATCH_NOT_TAIL_CALLED) [`var DISPATCH_ONCE_INLINE_FASTPATH: Int32`](/documentation/Dispatch/DISPATCH_ONCE_INLINE_FASTPATH) [`#define DISPATCH_OPTIONS(name, type, ...)`](/documentation/Dispatch/DISPATCH_OPTIONS) [`#define DISPATCH_OSX_SUPPORTS_AT_LEAST(macos, ios, tvos, watchos, bridgeos, visionos)`](/documentation/Dispatch/DISPATCH_OSX_SUPPORTS_AT_LEAST) [`#define DISPATCH_PURE`](/documentation/Dispatch/DISPATCH_PURE) [`#define DISPATCH_QUEUE_CONCURRENT_INACTIVE`](/documentation/Dispatch/DISPATCH_QUEUE_CONCURRENT_INACTIVE) [`#define DISPATCH_QUEUE_CONCURRENT_WITH_AUTORELEASE_POOL`](/documentation/Dispatch/DISPATCH_QUEUE_CONCURRENT_WITH_AUTORELEASE_POOL) [`#define DISPATCH_QUEUE_SERIAL_INACTIVE`](/documentation/Dispatch/DISPATCH_QUEUE_SERIAL_INACTIVE) [`#define DISPATCH_QUEUE_SERIAL_WITH_AUTORELEASE_POOL`](/documentation/Dispatch/DISPATCH_QUEUE_SERIAL_WITH_AUTORELEASE_POOL) [`#define DISPATCH_REFINED_FOR_SWIFT`](/documentation/Dispatch/DISPATCH_REFINED_FOR_SWIFT) [`#define DISPATCH_RETURNS_RETAINED`](/documentation/Dispatch/DISPATCH_RETURNS_RETAINED) [`#define DISPATCH_RETURNS_RETAINED_BLOCK`](/documentation/Dispatch/DISPATCH_RETURNS_RETAINED_BLOCK) [`#define DISPATCH_SENTINEL`](/documentation/Dispatch/DISPATCH_SENTINEL) [`#define DISPATCH_SIZED_BY(X)`](/documentation/Dispatch/DISPATCH_SIZED_BY) [`#define DISPATCH_SOURCE_DECL(name)`](/documentation/Dispatch/DISPATCH_SOURCE_DECL) [`#define DISPATCH_SOURCE_DECL_SWIFT(name, swift_name, protocol_name)`](/documentation/Dispatch/DISPATCH_SOURCE_DECL_SWIFT) [`#define DISPATCH_SOURCE_TYPE_DATA_REPLACE`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_DATA_REPLACE) [`#define DISPATCH_SOURCE_TYPE_DECL(name)`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_DECL) [`#define DISPATCH_SOURCE_TYPE_DECL_SWIFT(name, swift_name)`](/documentation/Dispatch/DISPATCH_SOURCE_TYPE_DECL_SWIFT) [`var DISPATCH_SWIFT3_OVERLAY: Int32`](/documentation/Dispatch/DISPATCH_SWIFT3_OVERLAY) [`#define DISPATCH_SWIFT3_UNAVAILABLE(_msg)`](/documentation/Dispatch/DISPATCH_SWIFT3_UNAVAILABLE) [`#define DISPATCH_SWIFT_NAME(_name)`](/documentation/Dispatch/DISPATCH_SWIFT_NAME) [`#define DISPATCH_SWIFT_UNAVAILABLE(_msg)`](/documentation/Dispatch/DISPATCH_SWIFT_UNAVAILABLE) [`#define DISPATCH_TARGET_QUEUE_DEFAULT`](/documentation/Dispatch/DISPATCH_TARGET_QUEUE_DEFAULT) [`#define DISPATCH_TRANSPARENT_UNION`](/documentation/Dispatch/DISPATCH_TRANSPARENT_UNION) [`#define DISPATCH_UNAVAILABLE`](/documentation/Dispatch/DISPATCH_UNAVAILABLE) [`#define DISPATCH_UNAVAILABLE_MSG(msg)`](/documentation/Dispatch/DISPATCH_UNAVAILABLE_MSG) [`#define DISPATCH_UNSAFE_INDEXABLE`](/documentation/Dispatch/DISPATCH_UNSAFE_INDEXABLE) [`#define DISPATCH_WARN_RESULT`](/documentation/Dispatch/DISPATCH_WARN_RESULT) [`var MSEC_PER_SEC: UInt64`](/documentation/Dispatch/MSEC_PER_SEC) [`#define dispatch_assert_queue_barrier_debug(q)`](/documentation/Dispatch/dispatch_assert_queue_barrier_debug) [`#define dispatch_assert_queue_debug(q)`](/documentation/Dispatch/dispatch_assert_queue_debug) [`#define dispatch_assert_queue_not_debug(q)`](/documentation/Dispatch/dispatch_assert_queue_not_debug) [`#define dispatch_cancel(object)`](/documentation/Dispatch/dispatch_cancel) [`#define dispatch_compiler_barrier()`](/documentation/Dispatch/dispatch_compiler_barrier) [`#define dispatch_notify(object, queue, notification_block)`](/documentation/Dispatch/dispatch_notify) [`#define dispatch_once`](/documentation/Dispatch/dispatch_once-c.macro) [`#define dispatch_once_f`](/documentation/Dispatch/dispatch_once_f-c.macro) [`#define dispatch_testcancel(object)`](/documentation/Dispatch/dispatch_testcancel) [`#define dispatch_wait(object, timeout)`](/documentation/Dispatch/dispatch_wait) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)