---
title: didChangeNotification
framework: foundation
role: symbol
role_heading: Type Property
path: foundation/userdefaults/didchangenotification
---

# didChangeNotification

Posted when the current process changes the value of a setting.

## Declaration

```swift
class let didChangeNotification: NSNotification.Name
```

## Mentioned in

Accessing settings from your code

## Discussion

Discussion When you write a new value to a setting, or remove an existing value, the system generates this notification to alert you that your app’s settings changed. Use this notification in other parts of your app to incorporate updated settings. The system posts this notification on the same thread you used to make the change. If a different process changes your app’s settings, the system doesn’t generate this notification. To detect changes made by another process, register a key-value observer on the UserDefaults object. Key-value observing reports all updates to setting values, regardless of which process made the change.

## See Also

### Monitoring settings changes and issues

- [UserDefaults.DidChangeMessage](foundation/userdefaults/didchangemessage.md)
- [UserDefaults.SizeLimitExceededMessage](foundation/userdefaults/sizelimitexceededmessage.md)
- [sizeLimitExceededNotification](foundation/userdefaults/sizelimitexceedednotification.md)