---
title: "requestReadData(from:atOffset:length:readDelegate:didReadDataSelector:contextInfo:)"
framework: imagecapturecore
role: symbol
role_heading: Instance Method
path: "imagecapturecore/iccameradevice/requestreaddata(from:atoffset:length:readdelegate:didreaddataselector:contextinfo:)"
---

# requestReadData(from:atOffset:length:readDelegate:didReadDataSelector:contextInfo:)

Asynchronously reads data of a specified length from a specified offset.

## Declaration

```swift
func requestReadData(from file: ICCameraFile, atOffset offset: off_t, length: off_t, readDelegate: Any, didReadDataSelector selector: Selector, contextInfo: UnsafeMutableRawPointer?)
```

## Discussion

Discussion The readDelegate must implement a function with the signature didReadData(data:NSData, fromFile:ICCameraFile, error:NSError, contextInfo:Any), to be called when the request is completed.

## See Also

### Reading Files

- [contents](imagecapturecore/iccameradevice/contents.md)
- [mediaFiles](imagecapturecore/iccameradevice/mediafiles.md)
- [contentCatalogPercentCompleted](imagecapturecore/iccameradevice/contentcatalogpercentcompleted.md)
- [files(ofType:)](imagecapturecore/iccameradevice/files(oftype:).md)