---
title: key
framework: foundation
role: symbol
role_heading: Instance Property
path: foundation/nssortdescriptor/key
---

# key

The key that specifies the property to compare during sorting.

## Declaration

```swift
var key: String? { get }
```

## See Also

### Getting Information About a Sort Descriptor

- [ascending](foundation/nssortdescriptor/ascending.md)
- [keyPath](foundation/nssortdescriptor/keypath.md)
- [selector](foundation/nssortdescriptor/selector.md)
- [comparator](foundation/nssortdescriptor/comparator.md)