---
title: AUImplementorValueFromStringCallback
framework: audiotoolbox
role: symbol
role_heading: Type Alias
path: audiotoolbox/auimplementorvaluefromstringcallback
---

# AUImplementorValueFromStringCallback

A block called to convert a string to a parameter value.

## Declaration

```swift
typealias AUImplementorValueFromStringCallback = (AUParameter, String) -> AUValue
```

## Discussion

Discussion This block is only of interest to audio unit subclasses. The block returns the current value of the parameter. The block takes the following parameters:

## See Also

### Related Documentation

- [implementorValueFromStringCallback](audiotoolbox/auparameternode/implementorvaluefromstringcallback.md)

### Monitoring Parameter Changes

- [AUListenerCreateWithDispatchQueue(_:_:_:_:)](audiotoolbox/aulistenercreatewithdispatchqueue(_:_:_:_:).md)
- [AUListenerCreate(_:_:_:_:_:_:)](audiotoolbox/aulistenercreate(_:_:_:_:_:_:).md)
- [AUParameterListenerNotify(_:_:_:)](audiotoolbox/auparameterlistenernotify(_:_:_:).md)
- [AUParameterFormatValue(_:_:_:_:)](audiotoolbox/auparameterformatvalue(_:_:_:_:).md)
- [AUParameterSet(_:_:_:_:_:)](audiotoolbox/auparameterset(_:_:_:_:_:).md)
- [AUParameterValueFromLinear(_:_:)](audiotoolbox/auparametervaluefromlinear(_:_:).md)
- [AUParameterValueToLinear(_:_:)](audiotoolbox/auparametervaluetolinear(_:_:).md)
- [AUParameterListenerBlock](audiotoolbox/auparameterlistenerblock.md)
- [AUParameterListenerProc](audiotoolbox/auparameterlistenerproc.md)
- [AUParameterListenerRef](audiotoolbox/auparameterlistenerref.md)
- [AUImplementorDisplayNameWithLengthCallback](audiotoolbox/auimplementordisplaynamewithlengthcallback.md)
- [AUImplementorStringFromValueCallback](audiotoolbox/auimplementorstringfromvaluecallback.md)