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# AudioFileOpenWithCallbacks(_:_:_:_:_:_:_:)

Opens an existing file with callbacks you provide.

```
func AudioFileOpenWithCallbacks(_ inClientData: UnsafeMutableRawPointer, _ inReadFunc: AudioFile_ReadProc, _ inWriteFunc: AudioFile_WriteProc?, _ inGetSizeFunc: AudioFile_GetSizeProc, _ inSetSizeFunc: AudioFile_SetSizeProc?, _ inFileTypeHint: AudioFileTypeID, _ outAudioFile: UnsafeMutablePointer<AudioFileID?>) -> OSStatus
```

## Parameters

`inClientData`

A pointer to a constant passed to your callbacks. The constant should contain any information you use to manage the state for reading data from the file.

`inReadFunc`

A callback function invoked when the audio file object wants to read data.

`inWriteFunc`

A callback function called when the audio file object wants to write data.

`inGetSizeFunc`

A callback function called when the audio file object wants to know the file size.

`inSetSizeFunc`

A callback function called when the audio file object wants to set the file size.

`inFileTypeHint`

A hint about the type of the designated file. For files with no filename extension and without a type easily or uniquely determined from the data (ADTS,AC3), use this hint to indicate the file type. Otherwise, pass `0` for this parameter. The hint is only available in macOS versions 10.3.1 or greater. In versions prior to OS X 10.3.1, opening files such files fails.

`outAudioFile`

On output, a pointer to the newly opened file.

## Return Value

A result code. See Result Codes.

## See Also

[`AudioFileInitializeWithCallbacks(_:_:_:_:_:_:_:_:_:)`](/documentation/AudioToolbox/AudioFileInitializeWithCallbacks(_:_:_:_:_:_:_:_:_:))

Deletes the content of an existing file and assigns callbacks to the audio file object.


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