---
title: NSMapTableValueCallBacks
framework: foundation
role: symbol
role_heading: Structure
path: foundation/nsmaptablevaluecallbacks
---

# NSMapTableValueCallBacks

The function pointers used to configure behavior of NSMapTable with respect to value elements within a map table.

## Declaration

```swift
struct NSMapTableValueCallBacks
```

## Overview

Overview All functions must know the types of things in the map table to be able to operate on them. Sets of predefined call backs are described in NSMapTable.

## Topics

### Initializers

- [init()](foundation/nsmaptablevaluecallbacks/init().md)
- [init(retain:release:describe:)](foundation/nsmaptablevaluecallbacks/init(retain:release:describe:).md)

### Instance Properties

- [describe](foundation/nsmaptablevaluecallbacks/describe.md)
- [release](foundation/nsmaptablevaluecallbacks/release.md)
- [retain](foundation/nsmaptablevaluecallbacks/retain.md)

## Relationships

### Conforms To

- [BitwiseCopyable](swift/bitwisecopyable.md)

## See Also

### Data Types

- [NSMapEnumerator](foundation/nsmapenumerator.md)
- [NSMapTable](foundation/legacy-nsmaptable.md)
- [NSMapTableKeyCallBacks](foundation/nsmaptablekeycallbacks.md)
- [NSMapTableOptions](foundation/nsmaptableoptions.md)