<!--
{
  "availability" : [
    "macOS: 10.7.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "AppKit",
  "identifier" : "/documentation/AppKit/NSLayoutConstraint/identifier",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Property",
  "symbol" : {
    "kind" : "Instance Property",
    "modules" : [
      "AppKit"
    ],
    "preciseIdentifier" : "c:objc(cs)NSLayoutConstraint(py)identifier"
  },
  "title" : "identifier"
}
-->

# identifier

The name that identifies the constraint.

```
var identifier: String? { get set }
```

## Discussion

A constraint’s identifier is available in its description. Identifiers that start with `NS` are reserved by the system.

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)