---
title: ioSize
framework: fskit
role: symbol
role_heading: Instance Property
path: fskit/fsstatfsresult/iosize
---

# ioSize

A property for the optimal block size with which to perform I/O.

## Declaration

```swift
var ioSize: Int { get set }
```

## Discussion

Discussion For best performance, specify an ioSize that’s an even multiple of blockSize.