iOS kAudioFileUnsupportedDataFormatError while creating Audio File for recording

Question

I am using ExtAudioFileCreateWithURL and consistently get a runtime kAudioFileUnsupportedDataFormatError error when creating a Stereo LPCM Float32 Wave file. I insist that the same procedure works fine with a Mono (single channel) file. Any hints?

Here's the code snippet:

let audioType: AudioFileTypeID = kAudioFileWAVEType 
var recordingFormatStream = CAStreamBasicDescription(sampleRate: sampleRate, numChannels: 2, pcmf: .Float32, isInterleaved: false)!

err = ExtAudioFileCreateWithURL(audioFileRecordingURL,
                                    audioType,
                                    &recordingFormatStream,
                                    nil,
                                    AudioFileFlags.EraseFile.rawValue,
                                    &audioRecordingAudioFile)

noting that audioFileRecordingURL and audioRecordingAudioFile are correctly typed and set.

For the records, the recordingFormatStream contains:

mFormatFlags = kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked | kAudioFormatFlagIsFloat | kAudioFormatFlagIsNonInterleaved
mFormatID = kAudioFormatLinearPCM
mSampleRate: 44100.0
mBytesPerPacket: 4, mFramesPerPacket: 1, mBytesPerFrame: 4, mChannelsPerFrame: 2, mBitsPerChannel: 32, mReserved: 0

I insist that if I change the numChannels to 1, everything is fine! Using iOS 9.3 SDK.

Answer 1

After much struggle: The ExtAudioFile methods in SDK do not accept non-interleaved audio . I believe that this is somehow new!

Thanks to this post: Using ExtAudioFileWriteAsync() in callback function. Can't get to run