<!--
{
  "availability" : [
    "macOS: 27.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "Virtualization",
  "identifier" : "/documentation/Virtualization/VZDiskImageStorageDeviceAttachment/init(diskImage:cachingMode:synchronizationMode:)",
  "metadataVersion" : "0.1.0",
  "role" : "Initializer",
  "symbol" : {
    "kind" : "Initializer",
    "modules" : [
      "Virtualization"
    ],
    "preciseIdentifier" : "s:So34VZDiskImageStorageDeviceAttachmentC14VirtualizationE04diskB011cachingMode015synchronizationI0AB04DiskB3Kit0kB0C_So0ab7CachingI0VSo0ab15SynchronizationI0VtKcfc"
  },
  "title" : "init(diskImage:cachingMode:synchronizationMode:)"
}
-->

# init(diskImage:cachingMode:synchronizationMode:)

Initializes the attachment from a disk image.

```
convenience init(diskImage: DiskImage, cachingMode: VZDiskImageCachingMode = .automatic, synchronizationMode: VZDiskImageSynchronizationMode = .full) throws
```

## Parameters

`diskImage`

A diskImage object created using the <doc://com.apple.documentation/documentation/DiskImageKit> framework. It supports both single and stacked disk images.

`cachingMode`

The host-level [`VZDiskImageCachingMode`](/documentation/Virtualization/VZDiskImageCachingMode) policy for the disk image. This is independent of cache layers in the disk image stack.

`synchronizationMode`

How the disk image synchronizes with the underlying storage when the guest operating system flushes data, described by one of the available [`VZDiskImageSynchronizationMode`](/documentation/Virtualization/VZDiskImageSynchronizationMode) modes.

## Discussion

This initializer enables the use of <doc://com.apple.documentation/documentation/DiskImageKit/DiskImage> objects created with the <doc://com.apple.documentation/documentation/DiskImageKit> framework, including stacked images with cache and overlay layers.

The following example shows how to initialize a storage attachment object using a disk image.

```swift
    import Virtualization
    
    let imageURL = // A `URL` that references a disk image.
    let diskImage = try DiskImage(opening: .init(url: imageURL))
    let storageAttachment = try VZDiskImageStorageDeviceAttachment(diskImage: diskImage)
    
```

---

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)