<!--
{
  "availability" : [
    "iOS: 2.0.0 -",
    "iPadOS: 2.0.0 -",
    "macCatalyst: 13.0.0 -",
    "macOS: 10.0.0 -",
    "tvOS: 9.0.0 -",
    "visionOS: 1.0.0 -",
    "watchOS: 2.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "Foundation",
  "identifier" : "/documentation/Foundation/NSKeyedUnarchiverDelegate",
  "metadataVersion" : "0.1.0",
  "role" : "Protocol",
  "symbol" : {
    "kind" : "Protocol",
    "modules" : [
      "Foundation"
    ],
    "preciseIdentifier" : "c:objc(pl)NSKeyedUnarchiverDelegate"
  },
  "title" : "NSKeyedUnarchiverDelegate"
}
-->

# NSKeyedUnarchiverDelegate

The optional methods implemented by the delegate of a keyed unarchiver.

```
protocol NSKeyedUnarchiverDelegate : NSObjectProtocol
```

## Topics

### Decoding Objects

[`-  unarchiver:cannotDecodeObjectOfClassName:originalClasses:`](/documentation/Foundation/NSKeyedUnarchiverDelegate/unarchiver(_:cannotDecodeObjectOfClassName:originalClasses:))

Informs the delegate that the class with a given name is not available during decoding.

[`-  unarchiver:didDecodeObject:`](/documentation/Foundation/NSKeyedUnarchiverDelegate/unarchiver(_:didDecode:))

Informs the delegate that a given object has been decoded.

[`-  unarchiver:willReplaceObject:withObject:`](/documentation/Foundation/NSKeyedUnarchiverDelegate/unarchiver(_:willReplace:with:))

Informs the delegate that one object is being substituted for another.

### Finishing Decoding

[`-  unarchiverDidFinish:`](/documentation/Foundation/NSKeyedUnarchiverDelegate/unarchiverDidFinish(_:))

Notifies the delegate that decoding has finished.

[`-  unarchiverWillFinish:`](/documentation/Foundation/NSKeyedUnarchiverDelegate/unarchiverWillFinish(_:))

Notifies the delegate that decoding is about to finish.

## Relationships

### Inherits From

[`NSObjectProtocol`](/documentation/ObjectiveC/NSObjectProtocol)

---

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)