---
title: "critical(_:)"
framework: os
role: symbol
role_heading: Instance Method
path: "os/logger/critical(_:)"
---

# critical(_:)

Writes a message to the log about a critical event in your app’s execution.

## Declaration

```swift
func critical(_ message: OSLogMessage)
```

## Parameters

- `message`: The interpolated string that the logger writes to the log. Each of the message’s interpolations can specify individual formatting and privacy options. For more information, see doc://com.apple.os/documentation/os/message-argument-formatters.

## Discussion

Discussion important: Don’t create an instance of OSLogMessage. Instead, provide an interpolated string as the message parameter and the system converts it automatically. This method is functionally equivalent to the fault(_:) method.

## See Also

### Logging a Scoped Message

- [notice(_:)](os/logger/notice(_:).md)
- [debug(_:)](os/logger/debug(_:).md)
- [trace(_:)](os/logger/trace(_:).md)
- [info(_:)](os/logger/info(_:).md)
- [error(_:)](os/logger/error(_:).md)
- [warning(_:)](os/logger/warning(_:).md)
- [fault(_:)](os/logger/fault(_:).md)