---
title: kSpeechWordCFCallBack
framework: applicationservices
role: symbol
role_heading: Global Variable
path: applicationservices/kspeechwordcfcallback
---

# kSpeechWordCFCallBack

Set the callback function to be called every time the Speech Synthesis Manager is about to generate a word on the speech channel.

## Declaration

```swift
let kSpeechWordCFCallBack: CFString
```

## Discussion

Discussion  The value associated with this property is CFNumber object whose value is a pointer to an application-defined word callback function, whose syntax is described in SpeechWordCFProcPtr. Passing a CFNumber object that contains the value NULL for the value of this property disables the word callback function. This property works with the SetSpeechProperty(_:_:_:) function.