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# DISPATCH_BLOCK_BARRIER

Cause the work item to act as a barrier block when submitted to a concurrent queue.

```
DISPATCH_BLOCK_BARRIER
```

## Discussion

Indicates that a dispatch block should act as a barrier block when submitted to a [`DISPATCH_QUEUE_CONCURRENT`](/documentation/Dispatch/DISPATCH_QUEUE_CONCURRENT) queue. See [`dispatch_barrier_async`](/documentation/Dispatch/dispatch_barrier_async) for details. This flag has no effect when the dispatch block is invoked directly.

---

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