---
title: "fill(buffer:range:value:)"
framework: metal
role: symbol
role_heading: Instance Method
path: "metal/mtlblitcommandencoder/fill(buffer:range:value:)"
---

# fill(buffer:range:value:)

Encodes a command that fills a buffer with a constant value for each byte.

## Declaration

```swift
func fill(buffer: any MTLBuffer, range: Range<Int>, value: UInt8)
```

## Parameters

- `buffer`: A buffer instance the command assigns each byte in range to value.
- `range`: A range of bytes within the buffer the command assigns value to. The range’s doc://com.apple.documentation/documentation/Swift/Collection/count property needs to be greater than 0. The range’s doc://com.apple.documentation/documentation/Swift/Collection/count, doc://com.apple.documentation/documentation/Swift/Range/lowerBound, and doc://com.apple.documentation/documentation/Swift/Range/upperBound properties need to be a multiple of 4 in macOS, but can be any value in iOS and tvOS.
- `value`: The value to write to each byte.