---
title: SecTransformAttributeActionBlock
framework: security
role: symbol
role_heading: Type Alias
path: security/sectransformattributeactionblock
---

# SecTransformAttributeActionBlock

A block used to override the default attribute handling for when an attribute is set.

## Declaration

```swift
typealias SecTransformAttributeActionBlock = (SecTransformAttribute, CFTypeRef) -> Unmanaged<CFTypeRef>?
```

## Parameters

- `attribute`: The attribute whose default is being overridden or NULL if this is a generic notification override
- `value`: Proposed new value for the attribute.

## Return Value

Return Value The new value of the attribute if successful or a CFError object on failure. If a transform needs to have a CFError as the value of an attribute, then place the object in a container, such as a CFArray or CFDictionary object.