AVAudioFile only saves zeroes?

Basically I need to create a 4 channel buffer, and output and read data to and from a file. I'm using PCM with a .CAF file since I'm not sure any other format that supports 4 channel audio (if that one even does?) I can create the buffer OK, but when it gets saved, the .CAF file is filled with zeroes, and when I read it back in, it prints all zeroes. I need a low sample rate since this is actually medical data. I What am I missing??

import AVFoundation

func createBuffer(_ outBuffer:AVAudioPCMBuffer) {
    let outputBuffer = UnsafeMutableAudioBufferListPointer(outBuffer.mutableAudioBufferList)
    var counter:Float = 1
    outBuffer.frameLength = outBuffer.frameCapacity
    for buffer in outputBuffer {
        guard let data = buffer.mData?.assumingMemoryBound(to: Float32.self) else { continue }
        
        for i in 0..<outBuffer.frameCapacity {
            data.advanced(by: Int(i)).pointee = counter
            counter += 1
        }
    }
}

func testExample() {
    let format2 = AVAudioFormat(
        commonFormat: .pcmFormatFloat32,
        sampleRate: 220,
        interleaved: false,
        channelLayout: AVAudioChannelLayout(layoutTag: kAudioChannelLayoutTag_Quadraphonic)!)
    
    let bufferSize:UInt32 = 10
    guard let outBuffer = AVAudioPCMBuffer(pcmFormat: format2, frameCapacity: bufferSize) else { print("outBuffer bad"); return }
    
    createBuffer(outBuffer)
    
    // Save matrix to .CAF file
    let fm = FileManager.default
    let doc = try! fm.url(for:.documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
    let fileURL = doc.appendingPathComponent("myfile.caf", isDirectory:false)
    try? fm.removeItem(at: fileURL) // just in case
    
    do {
        let outFile = try AVAudioFile(forWriting: fileURL, settings: outBuffer.format.settings)
        try outFile.write(from:outBuffer)
    } catch {
        print(error)
    }
    
    // Read, Convert .CAF file to MLMultiArray
    guard let infile = try? AVAudioFile(forReading: fileURL),
        let inBuffer = AVAudioPCMBuffer(pcmFormat: infile.processingFormat, frameCapacity: UInt32(infile.length)) else { return }
    
    
    let test = UnsafeBufferPointer<UnsafeMutablePointer<Float>>(start:inBuffer.floatChannelData, count:Int(inBuffer.format.channelCount))
    for buffer in test {
        let floats = UnsafeBufferPointer<Float>(start:buffer, count:Int(inBuffer.frameCapacity))
        for (index, value) in floats.enumerated() {
            print("value \(index): \(value)")
        }
    }
}

testExample()