---
title: Dispatch Constants
framework: Dispatch
role: collectionGroup
role_heading: API Collection
path: dispatch/dispatch-constants
---

# Dispatch Constants

## Topics

### Constants

- [DISPATCH_API_VERSION](dispatch/dispatch_api_version.md)
- [DISPATCH_APPLY_AUTO_AVAILABLE](dispatch/dispatch_apply_auto_available.md)
- [DISPATCH_ONCE_INLINE_FASTPATH](dispatch/dispatch_once_inline_fastpath.md)
- [DISPATCH_SWIFT3_OVERLAY](dispatch/dispatch_swift3_overlay.md)
- [MSEC_PER_SEC](dispatch/msec_per_sec.md)

## See Also

### Reference

- [Dispatch Data Types](dispatch/dispatch-data-types.md)
- [Dispatch Functions](dispatch/dispatch-functions.md)