---
title: compressedBytes
framework: appmigrationkit
role: symbol
role_heading: Instance Property
path: appmigrationkit/appmigrationtester/devicetodeviceexportproperties/compressedbytes
---

# compressedBytes

The number of compressed bytes written to the migration infrastructure, if the extension uses compression.

## Declaration

```swift
let compressedBytes: Int?
```

## Discussion

Discussion Use this information in testing to determine if your extension might benefit from data compression during migration. If the extension doesn’t use compression, this property is nil.

## See Also

### Inspecting data size properties

- [uncompressedBytes](appmigrationkit/appmigrationtester/devicetodeviceexportproperties/uncompressedbytes.md)
- [sizeEstimate](appmigrationkit/appmigrationtester/devicetodeviceexportproperties/sizeestimate.md)