---
title: "decompress(using:)"
framework: foundation
role: symbol
role_heading: Instance Method
path: "foundation/nsmutabledata/decompress(using:)"
---

# decompress(using:)

Decompresses the data object’s bytes.

## Declaration

```swift
func decompress(using algorithm: NSData.CompressionAlgorithm) throws
```

## Parameters

- `algorithm`: The algorithm to use for decompressing the data. For a list of available algorithms, see doc://com.apple.foundation/documentation/Foundation/NSData/CompressionAlgorithm.

## Discussion

Discussion Use this method to inflate in-memory data when you need uncompressed bytes. Specify the same algorithm used to compress the data to successfully decompress it. The following example shows how to inflate an instance of NSMutableData compressed with the NSData.CompressionAlgorithm.zlib algorithm: do {     data.decompress(using: .zlib) } catch {     print ("Decompression error: \(error)") }

## See Also

### Compressing and Decompressing Data

- [compress(using:)](foundation/nsmutabledata/compress(using:).md)
- [NSData.CompressionAlgorithm](foundation/nsdata/compressionalgorithm.md)
- [NSCompressionErrorMaximum](foundation/nscompressionerrormaximum-swift.var.md)
- [NSCompressionErrorMinimum](foundation/nscompressionerrorminimum-swift.var.md)
- [NSCompressionFailedError](foundation/nscompressionfailederror-swift.var.md)
- [NSDecompressionFailedError](foundation/nsdecompressionfailederror-swift.var.md)