---
title: os_signpost_id_t
framework: os
role: symbol
role_heading: Type Alias
path: os/os_signpost_id_t
---

# os_signpost_id_t

An identifier you use to distinguish between signposts that have the same name and destination log.

## Declaration

```swift
typealias os_signpost_id_t = UInt64
```

## Discussion

Discussion Multiple intervals with matching log objects and interval names can be in-flight simultaneously. In order for data-processing tools to correctly match the beginning and end of an interval, you need to identify each interval with a unique signpost identifier. Use the first strategy in the list below that matches your use case: If you can guarantee that intervals with the same log and name can never overlap in time, specify OS_SIGNPOST_ID_EXCLUSIVE as the signpost ID. If you already have your own integer data that can uniquely identify each instance of the task being measured, cast the data from a uint64_t value directly to a os_signpost_id_t. The value must not match one of the predefined signpost values. If you have a pointer that can uniquely identify begin/end pairs (such as a pointer to a data object used by the code being measured), call os_signpost_id_make_with_pointer. Don’t use this function for signposts that span process boundaries. Otherwise, call os_signpost_id_generate each time you create a new pair of signposts to generate a unique value for that pair.

## See Also

### Measure Events

- [Recording Performance Data](os/recording-performance-data.md)
- [OSSignposter](os/ossignposter.md)
- [Legacy Signpost Symbols](os/legacy-signpost-symbols.md)
- [OSSignpostType](os/ossignposttype.md)