AVAudioRecorder initWithURL file type documentatio

问题:

AvAudioRecorder has an init method:

- (instancetype)initWithURL:(NSURL *)url
                   settings:(NSDictionary *)settings
                      error:(NSError **)outError

And a "magic" behavior is partially documented:

URL

The file system location to record to. The file type to record to is inferred from the file extension included in this parameter’s value.

Is there any further documentation of this feature? Specifically, what are the supported file extensions? And is there any way to support raw output?

Related:

• How to record using AVAudioRecorder without the .caf container?
• How to use AVAudioRecorder data and convert it to raw audio for C++?
• How can I Access/extract raw(headless) audio data from a caf file on iPhone?