<!--
{
  "availability" : [
    "iOS: 8.0.0 -",
    "iPadOS: 8.0.0 -",
    "macCatalyst: 13.0.0 -",
    "macOS: 10.10.0 -",
    "tvOS: 9.0.0 -",
    "visionOS: 1.0.0 -",
    "watchOS: 2.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "Swift",
  "identifier" : "/documentation/Swift/KeyedDecodingContainerProtocol/nestedUnkeyedContainer(forKey:)",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Method",
  "symbol" : {
    "kind" : "Instance Method",
    "modules" : [
      "Swift"
    ],
    "preciseIdentifier" : "s:s30KeyedDecodingContainerProtocolP013nestedUnkeyedC06forKeys0fbC0_p0H0Qz_tKF"
  },
  "title" : "nestedUnkeyedContainer(forKey:)"
}
-->

# nestedUnkeyedContainer(forKey:)

Returns the data stored for the given key as represented in an unkeyed
container.

```
func nestedUnkeyedContainer(forKey key: Self.Key) throws -> any UnkeyedDecodingContainer
```

## Parameters

`key`

The key that the nested container is associated with.

## Return Value

An unkeyed decoding container view into `self`.

## Discussion> throws: `DecodingError.typeMismatch` if the encountered stored value is
> not an unkeyed container.

---

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)