---
title: "init(forReadingWith:)"
framework: foundation
role: symbol
role_heading: Initializer
path: "foundation/nsunarchiver/init(forreadingwith:)"
---

# init(forReadingWith:)

Returns an NSUnarchiver object initialized to read an archive from a given data object.

## Declaration

```swift
init?(forReadingWith data: Data)
```

## Parameters

- `data`: The archive data.

## Return Value

Return Value An NSUnarchiver object initialized to read an archive from data. Returns nil if data is not a valid archive.

## Discussion

Discussion The method decodes the system version number that was archived in data prepares the NSUnarchiver object for a subsequent invocation of decodeObject(). Raises an NSInvalidArgumentException if data is nil.

## See Also

### Related Documentation

- [Archives and Serializations Programming Guide](apple-archive/documentation/Cocoa/Conceptual/Archiving.md)
- [systemVersion](foundation/nsunarchiver/systemversion-swift.property.md)