---
title: CFXMLParserResolveExternalEntityCallBack
framework: Core Foundation
role: symbol
role_heading: Type Alias
path: corefoundation/cfxmlparserresolveexternalentitycallback
---

# CFXMLParserResolveExternalEntityCallBack

Callback function invoked by the parser to notify your application that an external entity has been referenced.

## Declaration

```swift
typealias CFXMLParserResolveExternalEntityCallBack = (CFXMLParser?, UnsafeMutablePointer<CFXMLExternalID>?, UnsafeMutableRawPointer?) -> Unmanaged<CFData>?
```

## Parameters

- `parser`: The CFXMLParser object making the callback.
- `extID`: The identifier for the external entity.
- `info`: The program-defined context data you specified in the doc://com.apple.corefoundation/documentation/CoreFoundation/CFXMLParserContext structure when creating the parser.

## Return Value

Return Value The external entity or NULL if it should not be resolved.

## Discussion

Discussion If this callback is not defined, the parser uses its internal routines to try and resolve the entity. Otherwise, if this callback returns NULL, a place holder for the external entity is inserted into the tree. In this manner, the parser’s client can prevent any external network or file accesses. This callback is optional.

## See Also

### Callbacks

- [CFXMLParserAddChildCallBack](corefoundation/cfxmlparseraddchildcallback.md)
- [CFXMLParserCopyDescriptionCallBack](corefoundation/cfxmlparsercopydescriptioncallback.md)
- [CFXMLParserCreateXMLStructureCallBack](corefoundation/cfxmlparsercreatexmlstructurecallback.md)
- [CFXMLParserEndXMLStructureCallBack](corefoundation/cfxmlparserendxmlstructurecallback.md)
- [CFXMLParserHandleErrorCallBack](corefoundation/cfxmlparserhandleerrorcallback.md)
- [CFXMLParserReleaseCallBack](corefoundation/cfxmlparserreleasecallback.md)
- [CFXMLParserRetainCallBack](corefoundation/cfxmlparserretaincallback.md)