# ExtAudioFileWrite(_:_:_:) Performs a synchronous, sequential write operation on an audio file. ``` func ExtAudioFileWrite(_ inExtAudioFile: ExtAudioFileRef, _ inNumberFrames: UInt32, _ ioData: UnsafePointer) -> OSStatus ``` ## Parameters `inExtAudioFile` The extended audio file object that represents the file to write to. `inNumberFrames` The number of frames to write. `ioData` The buffer(s) from which audio data is written to the file. ## Return Value A result code. ## Discussion If the extended audio file object has an application data format, then the object’s converter converts the data in the `ioData` parameter to the file data format. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)