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# CFStreamPropertyKey

```
struct CFStreamPropertyKey
```

## Topics

### Type Properties

[`appendToFile`](/documentation/CoreFoundation/CFStreamPropertyKey/appendToFile)

Value is a `CFBoolean` value that indicates whether to append the written data to a file, if it already exists, rather than to replace its contents.

[`dataWritten`](/documentation/CoreFoundation/CFStreamPropertyKey/dataWritten)

Value is a `CFData` object that contains all the bytes written to a writable memory stream. You cannot modify this value.

[`fileCurrentOffset`](/documentation/CoreFoundation/CFStreamPropertyKey/fileCurrentOffset)

Value is a `CFNumber` object containing the current file offset.

[`socketNativeHandle`](/documentation/CoreFoundation/CFStreamPropertyKey/socketNativeHandle)

Value is a `CFData` object that contains the native handle for a socket stream—of type [`CFSocketNativeHandle`](/documentation/CoreFoundation/CFSocketNativeHandle)—to which the socket stream is connected.

[`socketRemoteHostName`](/documentation/CoreFoundation/CFStreamPropertyKey/socketRemoteHostName)

Value is a `CFString` object containing the name of the host to which the socket stream is connected or `NULL` if unknown.

[`socketRemotePortNumber`](/documentation/CoreFoundation/CFStreamPropertyKey/socketRemotePortNumber)

Value is a `CFNumber` object containing the remote port number to which the socket stream is connected or `NULL` if unknown.


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