---
title: blackBlock
framework: corevideo
role: symbol
role_heading: Instance Property
path: corevideo/cvpixelformatdescription/pixellayout/blackblock
---

# blackBlock

The bit pattern for a block of black pixels.  If absent, black is assumed to be all zeros. Otherwise, this should be bitsPerBlock bits long. If bitsPerBlock is less than a byte, repeat the bit pattern for the full byte.

## Declaration

```swift
var blackBlock: Data?
```