<!--
{
  "availability" : [
    "iOS: 26.0.0 -",
    "iPadOS: 26.0.0 -",
    "macCatalyst: -",
    "macOS: 26.0.0 -",
    "tvOS: 26.0.0 -",
    "visionOS: 26.0.0 -",
    "watchOS: 26.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "CoreMedia",
  "identifier" : "/documentation/CoreMedia/CMSampleBuffer/SampleAttachments-swift.struct/isPartialSync",
  "metadataVersion" : "0.1.0",
  "role" : "Instance Property",
  "symbol" : {
    "kind" : "Instance Property",
    "modules" : [
      "Core Media"
    ],
    "preciseIdentifier" : "s:So17CMSampleBufferRefa9CoreMediaE17SampleAttachmentsV13isPartialSyncSbvp"
  },
  "title" : "isPartialSync"
}
-->

# isPartialSync

Indicates whether the sample is a partial sync sample.

```
var isPartialSync: Bool { get set }
```

## Discussion

A partial sync sample can be decoded without requiring any previous samples to have been decoded. Samples
following two consecutive partial sync samples also do not require samples prior to the pair to have been
decoded. To treat a sample as a partial sync sample, set to true for both this key and the `notSync` key.

This attachment is read from and written to media files.

---

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)