---
title: powerStateDidChange
framework: foundation
role: symbol
role_heading: Type Property
path: foundation/notificationcenter/messageidentifier/powerstatedidchange
---

# powerStateDidChange

An identifier for a message about a power state change.

## Declaration

```swift
static var powerStateDidChange: NotificationCenter.BaseMessageIdentifier<ProcessInfo.PowerStateDidChangeMessage> { get }
```

## Discussion

Discussion Use this identifier with NotificationCenter’s addObserver(of:for:using:) or messages(of:for:bufferSize:) methods to observe messages of type ProcessInfo.PowerStateDidChangeMessage.

## See Also

### Identifying process info messages

- [thermalStateDidChange](foundation/notificationcenter/messageidentifier/thermalstatedidchange.md)
- [didTerminate](foundation/notificationcenter/messageidentifier/didterminate.md)