---
title: describe
framework: foundation
role: symbol
role_heading: Instance Property
path: foundation/nsmaptablekeycallbacks/describe
---

# describe

Points to the function which produces an autoreleased NSString * describing the given element. If NULL, then the map table produces a generic string description.

## Declaration

```swift
var describe: ((NSMapTable<AnyObject, AnyObject>, UnsafeRawPointer) -> String?)?
```