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# OSLog

A unified logging system for the reading of historical data.

## Overview

The OSLog framework allows you to read logs. With the unified logging system, you can build custom debugging and analysis tools to be used alongside Apple tools like Instruments and Console. To learn more about how to create logs, see <doc://com.apple.documentation/documentation/os/logging>.

## Topics

### Read Log Entries

[`OSLogStore`](/documentation/OSLog/OSLogStore)

A set of entries from the unified logging system.

[`OSLogEnumerator`](/documentation/OSLog/OSLogEnumerator)

An enumerator that can access and list log entries.

### Log Entries

[`OSLogEntry`](/documentation/OSLog/OSLogEntry)

A single entry from the unified logging system.

[`OSLogEntryActivity`](/documentation/OSLog/OSLogEntryActivity)

An entry generated by an activity event.

[`OSLogEntryBoundary`](/documentation/OSLog/OSLogEntryBoundary)

The metadata that partitions sequences of other entries.

[`OSLogEntryLog`](/documentation/OSLog/OSLogEntryLog)

A log entry.

[`OSLogEntrySignpost`](/documentation/OSLog/OSLogEntrySignpost)

An entry containing a signpost.

[`OSLogEntryFromProcess`](/documentation/OSLog/OSLogEntryFromProcess)

A protocol that defines subclasses containing metadata about a process.

[`OSLogEntryWithPayload`](/documentation/OSLog/OSLogEntryWithPayload)

A protocol defining subclasses that represent entries made using a handle and a format string.

### Entry Data

[`OSLogMessageComponent`](/documentation/OSLog/OSLogMessageComponent)

The message arguments for a particular entry.

[`OSLogPosition`](/documentation/OSLog/OSLogPosition)

A representation of a point in a sequence of entries in the unified logging system.

### Reference

[OSLog Enumerations](/documentation/OSLog/oslog-enumerations)


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