---
title: UITraitChangeHandler
framework: uikit
role: symbol
role_heading: Type Alias
path: uikit/uitraitchangehandler
---

# UITraitChangeHandler

## Declaration

```occ
typedef void (^)(__kindof id<UITraitEnvironment>, UITraitCollection *) UITraitChangeHandler;
```

## See Also

### Observing trait changes

- [registerForTraitChanges:withAction:](uikit/uitraitchangeobservable-7qoet/registerfortraitchanges:withaction:.md)
- [registerForTraitChanges:withHandler:](uikit/uitraitchangeobservable-7qoet/registerfortraitchanges:withhandler:.md)
- [registerForTraitChanges:withTarget:action:](uikit/uitraitchangeobservable-7qoet/registerfortraitchanges:withtarget:action:.md)
- [unregisterForTraitChanges:](uikit/uitraitchangeobservable-7qoet/unregisterfortraitchanges:.md)
- [UITraitChangeRegistration](uikit/uitraitchangeregistration.md)