---
title: "init(retain:release:describe:)"
framework: foundation
role: symbol
role_heading: Initializer
path: "foundation/nsmaptablevaluecallbacks/init(retain:release:describe:)"
---

# init(retain:release:describe:)

## Declaration

```swift
init(retain: ((NSMapTable<AnyObject, AnyObject>, UnsafeRawPointer) -> Void)?, release: ((NSMapTable<AnyObject, AnyObject>, UnsafeMutableRawPointer) -> Void)?, describe: ((NSMapTable<AnyObject, AnyObject>, UnsafeRawPointer) -> String?)?)
```