---
title: "SecTransformRegister(_:_:_:)"
framework: security
role: symbol
role_heading: Function
path: "security/sectransformregister(_:_:_:)"
---

# SecTransformRegister(_:_:_:)

Registers a custom transform.

## Declaration

```swift
func SecTransformRegister(_ uniqueName: CFString, _ createTransformFunction: SecTransformCreateFP, _ error: UnsafeMutablePointer<Unmanaged<CFError>?>?) -> Bool
```

## Parameters

- `uniqueName`: A unique name for this custom transform. It is recommended that a reverse DNS name be used for the name of your custom transform
- `createTransformFunction`: A doc://com.apple.security/documentation/Security/SecTransformCreateFP function pointer. The function must return a doc://com.apple.security/documentation/Security/SecTransformInstanceBlock block. Call block_copy on this block before returning it. Failure to do so results in undefined behavior.
- `error`: A pointer that the function uses to provide an error object with details if an error occurs. The caller becomes responsible for the object’s memory. Pass NULL to ignore the error.

## Return Value

Return Value A Boolean that is set to true if the custom transform was registered and false otherwise