---
title: retain
framework: systemconfiguration
role: symbol
role_heading: Instance Property
path: systemconfiguration/scnetworkreachabilitycontext/retain
---

# retain

The callback used to add a retain for the info field. If this parameter is not a pointer to a function of the correct prototype, the behavior is undefined. The value can be NULL.

## Declaration

```swift
var retain: ((UnsafeRawPointer) -> UnsafeRawPointer)?
```