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# kSecTransformActionAttributeNotification

An action that triggers when an attribute is set.

```
let kSecTransformActionAttributeNotification: CFString
```

## Discussion

Allows a block to be called when an attribute is set. This allows for caching the value as a block variable in the instance block or transmogrifying the data to be set. This action is where a custom transform would be able to do processing outside of processing input to output as process data does. One the data has been processed the action block can call SecTransformCustomSetAttribute to update and other attribute.

---

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