blcok.h

DISPATCH_ENUM(dispatch_block_flags, unsigned long,
    DISPATCH_BLOCK_BARRIER
            DISPATCH_ENUM_AVAILABLE_STARTING(__MAC_10_10, __IPHONE_8_0) = 0x1,
    DISPATCH_BLOCK_DETACHED
            DISPATCH_ENUM_AVAILABLE_STARTING(__MAC_10_10, __IPHONE_8_0) = 0x2,
    DISPATCH_BLOCK_ASSIGN_CURRENT
            DISPATCH_ENUM_AVAILABLE_STARTING(__MAC_10_10, __IPHONE_8_0) = 0x4,
    DISPATCH_BLOCK_NO_QOS_CLASS
            DISPATCH_ENUM_AVAILABLE_STARTING(__MAC_10_10, __IPHONE_8_0) = 0x8,
    DISPATCH_BLOCK_INHERIT_QOS_CLASS
            DISPATCH_ENUM_AVAILABLE_STARTING(__MAC_10_10, __IPHONE_8_0) = 0x10,
    DISPATCH_BLOCK_ENFORCE_QOS_CLASS
            DISPATCH_ENUM_AVAILABLE_STARTING(__MAC_10_10, __IPHONE_8_0) = 0x20,
);

dispatch_block_t
dispatch_block_create(dispatch_block_flags_t flags, dispatch_block_t block);


__OSX_AVAILABLE_STARTING(__MAC_10_10, __IPHONE_8_0)
DISPATCH_EXPORT DISPATCH_NONNULL4 DISPATCH_RETURNS_RETAINED_BLOCK
DISPATCH_WARN_RESULT DISPATCH_NOTHROW
dispatch_block_t
dispatch_block_create_with_qos_class(dispatch_block_flags_t flags,
        dispatch_qos_class_t qos_class, int relative_priority,
        dispatch_block_t block);

void
dispatch_block_perform(dispatch_block_flags_t flags,
        DISPATCH_NOESCAPE dispatch_block_t block);

long
dispatch_block_wait(dispatch_block_t block, dispatch_time_t timeout);


void
dispatch_block_notify(dispatch_block_t block, dispatch_queue_t queue,
        dispatch_block_t notification_block);

void
dispatch_block_cancel(dispatch_block_t block);

DISPATCH_NOTHROW
long
dispatch_block_testcancel(dispatch_block_t block);