<!--
{
  "availability" : [
    "macOS: 10.6.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "CoreWLAN",
  "identifier" : "/documentation/CoreWLAN/CWInterface/setPairwiseMasterKey(_:)",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Method",
  "symbol" : {
    "kind" : "Instance Method",
    "modules" : [
      "Core WLAN"
    ],
    "preciseIdentifier" : "c:objc(cs)CWInterface(im)setPairwiseMasterKey:error:"
  },
  "title" : "setPairwiseMasterKey(_:)"
}
-->

# setPairwiseMasterKey(_:)

Sets the interface pairwise primary key (PMK).

```
func setPairwiseMasterKey(_ key: Data?) throws
```

## Parameters

`key`

An NSData object containing the pairwise primary key (PMK).

## Discussion

*key* must be 32 octets. If *key* is *nil*, this method clears the PMK for the interface.

> Handling Errors in Swift:
> In Swift, this method returns `Void` and is marked with the `throws` keyword to indicate that it throws an error in cases of failure.
> 
> You call this method in a `try` expression and handle any errors in the `catch` clauses of a `do` statement, as described in [Error Handling](https://docs.swift.org/swift-book/LanguageGuide/ErrorHandling.html) in [The Swift Programming Language](https://docs.swift.org/swift-book/) and `About Imported Cocoa Error Parameters`.

---

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)