Corrupted WAV Audio Files in iOS - Why?

Question

Corrupted WAV Audio Files in iOS - Why?

I write the WAV files and send them to the server, but the server does not seem to recognize and manipulate the WAV files recorded on the device - any other WAV file works. Interestingly, I did something wrong with any setting AVAudioRecorder.

let settings: [String:AnyObject] = [
     AVFormatIDKey: Int(kAudioFormatLinearPCM),
     AVSampleRateKey: 44100.0,
     AVNumberOfChannelsKey: 1,
     AVLinearPCMBitDepthKey: 16,
     AVLinearPCMIsBigEndianKey: true
]

This is the function that records the sound coming from the microphone:

var recordingSession: AVAudioSession!
var audioRecorder: AVAudioRecorder!
var audioURL = NSURL()

func startRecording() {
    recordingSession = AVAudioSession.sharedInstance()

    do {
        try recordingSession.setCategory(AVAudioSessionCategoryRecord)
        try recordingSession.setActive(true)
    } catch {
        // failed to record!
    }

    let audioFilename = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0]
    audioURL = audioFilename.URLByAppendingPathComponent("recording.wav")

     let settings: [String:AnyObject] = [
          AVFormatIDKey: Int(kAudioFormatLinearPCM),
          AVSampleRateKey: 44100.0,
          AVNumberOfChannelsKey: 1,
          AVLinearPCMBitDepthKey: 16,
          AVLinearPCMIsBigEndianKey: true
     ]

    do {
        audioRecorder = try AVAudioRecorder(URL: audioURL, settings: settings)
        audioRecorder.delegate = self
        audioRecorder.record()
        audioRecorder.meteringEnabled = true
        print("Recording...")
    } catch {
          // error
    }
}

// I'm done! Send file to server
func uploadFileAudioToServer() {
    let path = "recordings/" + "userNameGoesHere" + ".wav"
    amazonS3Manager.putObject(audioURL, destinationPath: path).responseS3Data({ (response) -> Void in
        print("File uploaded")
    })
}