Can't play a sound file downloaded from an S3 bucket - ios

Question

I am facing a weird problem with an .m4a sound file on an iOS app written in Swift.
Here is what happens:
I record a sound file on the device using the app. Let us call it xyz.m4a.
I check that I can play this sound file, and it is working.
I then upload the sound file to an AWS S3 bucket, from my app.
I check on the AWS console that the file is uploaded as expected and I download it using a browser (on my computer), checking again that I can still play the sound as expected. Up to this point nothing is wrong, I can play the sound.
I then use my app to download the file to my iOS device (iPhone 6). All seems OK here too.
Finally I try to play the downloaded file from within my app and this is where things go wrong. I cannot play it.
Here is what I think is the relevant code, please let me know if you think I should add more.
Code to download the file from the AWS S3 bucket:
let transferUtility = AWSS3TransferUtility.default()
transferUtility.downloadData(
fromBucket: "mybucket",
key: "xyz.m4a",
expression: expression,
completionHandler: completionHandler
).continueWith {
(task) -> AnyObject! in if let error = task.error {
print("Error: \(error.localizedDescription)")
}
if let _ = task.result {
// Do something with downloadTask.
print("task.result -- OK!")
let downloadOutput = task.result
print("downloadOutput:\(String(describing: downloadOutput))")
}
return nil;
}
Here is the completionHandler part:
var completionHandler: AWSS3TransferUtilityDownloadCompletionHandlerBlock?
completionHandler = {
[weak self] (task, URL, data, error) -> Void in
DispatchQueue.main.async(execute: {
print("transfer completion OK!")
let localFileName = "xyz.m4a",
playFileURL = self?.getDocumentsURL().appendingPathComponent(localFileName)
FileManager.default.createFile(atPath: (playFileURL?.path)!,
contents: data,
attributes: nil)
if FileManager.default.fileExists(atPath: (playFileURL?.path)!) {
print("playFileURL present!") // Confirm that the file is here!
}
})
}
Code to play the downloaded sound file:
let fileName = "xyz.m4a",
audioFile = getDocumentsURL().appendingPathComponent(fileName)
if !FileManager.default.fileExists(atPath: audioFile.path) {
print("We have no file !!!!!") // Just in case the file was not found!
}
// This code assumes the file exists.
do {try soundSession.setCategory(AVAudioSessionCategoryPlayback)
try soundSession.setActive(true)
if audioPlayer == nil {
audioPlayer = try AVAudioPlayer(contentsOf: audioFile,
fileTypeHint: AVFileType.m4a.rawValue)
guard let _ = audioPlayer else {return}
audioPlayer.delegate = self
}
audioPlayer.play()
} catch let error {
print("Error:\n" + error.localizedDescription)
}
Finally here is the error I get:
Error:
The operation couldn’t be completed. (OSStatus error 1685348671.)
I hope someone can see something wrong an tell me where the problem is.