---
title: "init(hash:isEqual:retain:release:describe:notAKeyMarker:)"
framework: foundation
role: symbol
role_heading: Initializer
path: "foundation/nsmaptablekeycallbacks/init(hash:isequal:retain:release:describe:notakeymarker:)"
---

# init(hash:isEqual:retain:release:describe:notAKeyMarker:)

## Declaration

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