---
title: "requestReadData(atOffset:length:completion:)"
framework: imagecapturecore
role: symbol
role_heading: Instance Method
path: "imagecapturecore/iccamerafile/requestreaddata(atoffset:length:completion:)"
---

# requestReadData(atOffset:length:completion:)

Requests to asynchronously read data of a specified length from a specified offset, then executes the completion block.

## Declaration

```swift
func requestReadData(atOffset offset: off_t, length: off_t, completion: @escaping @Sendable (Data?, (any Error)?) -> Void)
```

```swift
func requestReadData(atOffset offset: off_t, length: off_t) async throws -> Data
```

## Discussion

Discussion The completion block executes on an any available queue; often this is not the main queue.