---
title: kCMBlockBufferCustomBlockSourceVersion
framework: coremedia
role: symbol
role_heading: Global Variable
path: coremedia/kcmblockbuffercustomblocksourceversion
---

# kCMBlockBufferCustomBlockSourceVersion

The value is the block source version.

## Declaration

```swift
var kCMBlockBufferCustomBlockSourceVersion: UInt32 { get }
```