---
title: implementorValueObserver
framework: audiotoolbox
role: symbol
role_heading: Instance Property
path: audiotoolbox/auparameternode/implementorvalueobserver
---

# implementorValueObserver

The callback for parameter value changes.

## Declaration

```swift
var implementorValueObserver: AUImplementorValueObserver { get set }
```

## Discussion

Discussion This block receives all externally-generated changes to parameter values. It should store the new value in its audio signal processing state (assuming that state is separate from the parameter object).

## See Also

### Audio Unit Implementations

- [implementorValueProvider](audiotoolbox/auparameternode/implementorvalueprovider.md)
- [implementorStringFromValueCallback](audiotoolbox/auparameternode/implementorstringfromvaluecallback.md)
- [implementorValueFromStringCallback](audiotoolbox/auparameternode/implementorvaluefromstringcallback.md)
- [implementorDisplayNameWithLengthCallback](audiotoolbox/auparameternode/implementordisplaynamewithlengthcallback.md)