---
title: mutableContainers
framework: foundation
role: symbol
role_heading: Type Property
path: foundation/jsonserialization/readingoptions/mutablecontainers
---

# mutableContainers

Specifies that arrays and dictionaries in the returned object are mutable.

## Declaration

```swift
static var mutableContainers: JSONSerialization.ReadingOptions { get }
```

## See Also

### Reading Options

- [mutableLeaves](foundation/jsonserialization/readingoptions/mutableleaves.md)
- [fragmentsAllowed](foundation/jsonserialization/readingoptions/fragmentsallowed.md)
- [json5Allowed](foundation/jsonserialization/readingoptions/json5allowed.md)
- [topLevelDictionaryAssumed](foundation/jsonserialization/readingoptions/topleveldictionaryassumed.md)
- [allowFragments](foundation/jsonserialization/readingoptions/allowfragments.md)