---
title: valueFunction
framework: quartzcore
role: symbol
role_heading: Instance Property
path: quartzcore/capropertyanimation/valuefunction
---

# valueFunction

An optional value function that is applied to interpolated values.

## Declaration

```swift
var valueFunction: CAValueFunction? { get set }
```

## Discussion

Discussion If the valueFunction property is not nil, the function is applied to the values interpolated by the animation as they are applied to the presentation layer. Defaults to nil.

## See Also

### Property Value Calculation Behavior

- [isCumulative](quartzcore/capropertyanimation/iscumulative.md)
- [isAdditive](quartzcore/capropertyanimation/isadditive.md)