dispatch/group.h

@typedef dispatch_group_t @abstract A group of blocks submitted to queues for asynchronous invocation.

DISPATCH_DECL_SWIFT(dispatch_group, DispatchGroup)

API_AVAILABLE(macos(10.6), ios(4.0)) DISPATCH_EXPORT DISPATCH_MALLOC DISPATCH_RETURNS_RETAINED DISPATCH_WARN_RESULT DISPATCH_NOTHROW DISPATCH_SWIFT_NAME(DispatchGroup.init()) dispatch_group_t dispatch_group_create(
	void
)

@function dispatch_group_create @abstract Creates new group with which blocks may be associated. @discussion This function creates a new group with which blocks may be associated. The dispatch group may be used to wait for the completion of the blocks it references. The group object memory is freed with dispatch_release(). @result The newly created group, or NULL on failure.

API_AVAILABLE(macos(10.6), ios(4.0)) DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW DISPATCH_REFINED_FOR_SWIFT void dispatch_group_async(
	dispatch_group_t group,
	dispatch_queue_t queue,
	dispatch_block_t block
)

@function dispatch_group_async @abstract Submits a block to a dispatch queue and associates the block with the given dispatch group. @discussion Submits a block to a dispatch queue and associates the block with the given dispatch group. The dispatch group may be used to wait for the completion of the blocks it references. @param group A dispatch group to associate with the submitted block. The result of passing NULL in this parameter is undefined. @param queue The dispatch queue to which the block will be submitted for asynchronous invocation. @param block The block to perform asynchronously.

API_AVAILABLE(macos(10.6), ios(4.0)) DISPATCH_EXPORT DISPATCH_NONNULL1 DISPATCH_NONNULL2 DISPATCH_NONNULL4 DISPATCH_NOTHROW DISPATCH_SWIFT_UNAVAILABLE("Use DispatchQueue.async(self:group:qos:flags:execute:)") void dispatch_group_async_f(
	dispatch_group_t group,
	dispatch_queue_t queue,
	void *_Nullable context,
	dispatch_function_t work
)

@function dispatch_group_async_f @abstract Submits a function to a dispatch queue and associates the block with the given dispatch group. @discussion See dispatch_group_async() for details. @param group A dispatch group to associate with the submitted function. The result of passing NULL in this parameter is undefined. @param queue The dispatch queue to which the function will be submitted for asynchronous invocation. @param context The application-defined context parameter to pass to the function. @param work The application-defined function to invoke on the target queue. The first parameter passed to this function is the context provided to dispatch_group_async_f().

API_AVAILABLE(macos(10.6), ios(4.0)) DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW DISPATCH_REFINED_FOR_SWIFT intptr_t dispatch_group_wait(
	dispatch_group_t group,
	dispatch_time_t timeout
)

@function dispatch_group_wait @abstract Wait synchronously until all the blocks associated with a group have completed or until the specified timeout has elapsed. @discussion This function waits for the completion of the blocks associated with the given dispatch group, and returns after all blocks have completed or when the specified timeout has elapsed. This function will return immediately if there are no blocks associated with the dispatch group (i.e. the group is empty). The result of calling this function from multiple threads simultaneously with the same dispatch group is undefined. After the successful return of this function, the dispatch group is empty. It may either be released with dispatch_release() or re-used for additional blocks. See dispatch_group_async() for more information. @param group The dispatch group to wait on. The result of passing NULL in this parameter is undefined. @param timeout When to timeout (see dispatch_time). As a convenience, there are the DISPATCH_TIME_NOW and DISPATCH_TIME_FOREVER constants. @result Returns zero on success (all blocks associated with the group completed within the specified timeout) or non-zero on error (i.e. timed out).

API_AVAILABLE(macos(10.6), ios(4.0)) DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW DISPATCH_REFINED_FOR_SWIFT void dispatch_group_notify(
	dispatch_group_t group,
	dispatch_queue_t queue,
	dispatch_block_t block
)

@function dispatch_group_notify @abstract Schedule a block to be submitted to a queue when all the blocks associated with a group have completed. @discussion This function schedules a notification block to be submitted to the specified queue once all blocks associated with the dispatch group have completed. If no blocks are associated with the dispatch group (i.e. the group is empty) then the notification block will be submitted immediately. The group will be empty at the time the notification block is submitted to the target queue. The group may either be released with dispatch_release() or reused for additional operations. See dispatch_group_async() for more information. @param group The dispatch group to observe. The result of passing NULL in this parameter is undefined. @param queue The queue to which the supplied block will be submitted when the group completes. @param block The block to submit when the group completes.

API_AVAILABLE(macos(10.6), ios(4.0)) DISPATCH_EXPORT DISPATCH_NONNULL1 DISPATCH_NONNULL2 DISPATCH_NONNULL4 DISPATCH_NOTHROW DISPATCH_SWIFT_UNAVAILABLE("Use DispatchGroup.notify(self:qos:flags:queue:execute:)") void dispatch_group_notify_f(
	dispatch_group_t group,
	dispatch_queue_t queue,
	void *_Nullable context,
	dispatch_function_t work
)

@function dispatch_group_notify_f @abstract Schedule a function to be submitted to a queue when all the blocks associated with a group have completed. @discussion See dispatch_group_notify() for details. @param group The dispatch group to observe. The result of passing NULL in this parameter is undefined. @param context The application-defined context parameter to pass to the function. @param work The application-defined function to invoke on the target queue. The first parameter passed to this function is the context provided to dispatch_group_notify_f().

API_AVAILABLE(macos(10.6), ios(4.0)) DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW DISPATCH_SWIFT_NAME(DispatchGroup.enter(self:)) void dispatch_group_enter(
	dispatch_group_t group
)

@function dispatch_group_enter @abstract Manually indicate a block has entered the group @discussion Calling this function indicates another block has joined the group through a means other than dispatch_group_async(). Calls to this function must be balanced with dispatch_group_leave(). @param group The dispatch group to update. The result of passing NULL in this parameter is undefined.

API_AVAILABLE(macos(10.6), ios(4.0)) DISPATCH_EXPORT DISPATCH_NONNULL_ALL DISPATCH_NOTHROW DISPATCH_SWIFT_NAME(DispatchGroup.leave(self:)) void dispatch_group_leave(
	dispatch_group_t group
)

@function dispatch_group_leave @abstract Manually indicate a block in the group has completed @discussion Calling this function indicates block has completed and left the dispatch group by a means other than dispatch_group_async(). @param group The dispatch group to update. The result of passing NULL in this parameter is undefined.