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# NSFileHandleNotificationDataItem

A key in the userinfo dictionary in a [`readCompletionNotification`](/documentation/Foundation/FileHandle/readCompletionNotification) and [`NSFileHandleReadToEndOfFileCompletion`](/documentation/Foundation/NSNotification/Name-swift.struct/NSFileHandleReadToEndOfFileCompletion).

```
let NSFileHandleNotificationDataItem: String
```

## Discussion

The corresponding value is an `NSData` object containing the available data read from a socket connection.

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