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# OSLog

A container of related log messages.

```
class OSLog
```

## Overview

A log categorizes the messages you write and makes it easy to sort and filter them. Each log contains a subsystem and a category, which you define. A subsystem identifies a major functional area of your app, which you specify using reverse DNS notation, such as `com.your_company.your_subsystem_name`. A category segregates specific areas within a subsystem.

## Topics

### Creating a Log

[`init(subsystem:category:)`](/documentation/os/OSLog/init(subsystem:category:)-17gyy)

Creates a log using the specified subsystem and category.

[`init(subsystem:category:)`](/documentation/os/OSLog/init(subsystem:category:)-72ghw)

Creates a log using the specified subsystem and system-defined category.

[`OSLog.Category`](/documentation/os/OSLog/Category)

System-defined categories that identify well-known parts of your app.

### Getting the Shared Logs

[`default`](/documentation/os/OSLog/default)

The shared default log.

[`disabled`](/documentation/os/OSLog/disabled)

The shared disabled log.

### Getting Log Configuration

[`isEnabled(type:)`](/documentation/os/OSLog/isEnabled(type:))

Returns a Boolean value that indicates whether the log can write messages with the specified log type.

[`signpostsEnabled`](/documentation/os/OSLog/signpostsEnabled)

A Boolean value that indicates whether a log is able to use signpost logging.


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