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# dispatch_once_t

A predicate for use with the `dispatch_once` function.

```
typedef intptr_t dispatch_once_t;
```

## Discussion

Variables of this type must have global or static scope.  The result of using this type with automatic or dynamic allocation is undefined. See [`dispatch_get_global_queue`](/documentation/Dispatch/dispatch_get_global_queue) for details.

---

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