Can't record on iPad: Error Domain=NSOSStatusErrorDomain Code=1718449215 "(null)" - ios

Question

I am running on iPad iOS 9.3.4 (latest version as of this writing).
I am running this code:
let settings = [
AVFormatIDKey: NSNumber(unsignedInt: kAudioFormatMPEG4AAC),
AVSampleRateKey: 44100.0,
AVNumberOfChannelsKey: 2 as NSNumber,
AVEncoderAudioQualityKey: AVAudioQuality.High.rawValue
]
do {
audioRecorder = try AVAudioRecorder(URL: audioURL, settings: settings)
audioRecorder.delegate = self
audioRecorder.record()
} catch let error as NSError{
print(error.description)
}
I am catching this error:
Error Domain=NSOSStatusErrorDomain Code=1718449215 "(null)"
When I try to use AVAudioRecorder with Objective-C - I am able to record with no problems. The problem seems to only occur with Swift and only on a device - no issue in simulator.
If I switch out kAudioFormatMPEG4AAC with kAudioFormatLinearPCM, I am able to record - but when I try to play back the recording nothing plays - seems like it hasn't recorded well.
Has anyone been able to record with AVAudioRecorder in Swift lately and have the recording play back on a real iPad? I would like to just have that code.

Answer 1

Output file path extension must be in sync with AVFormatIDKey
For .wav
let recordSettings:[String:Any] = [AVFormatIDKey:kAudioFormatLinearPCM,
AVEncoderAudioQualityKey:AVAudioQuality.max.rawValue,
AVEncoderBitRateKey:320000,
AVNumberOfChannelsKey:2,
AVSampleRateKey:44100.0 ] as [String : Any]
For .m4a
let recordSettings:[String:Any] = [AVFormatIDKey:kAudioFormatAppleLossless,
AVEncoderAudioQualityKey:AVAudioQuality.max.rawValue,
AVEncoderBitRateKey:320000,
AVNumberOfChannelsKey:2,
AVSampleRateKey:44100.0 ] as [String : Any]

Answer 2

Looks like I never set the recording session as being active. I wish the error description was better though.
override init() {
super.init()
recordingSession = AVAudioSession.sharedInstance()
do {
try recordingSession.setCategory(AVAudioSessionCategoryPlayAndRecord)
try recordingSession.setActive(true)
recordingSession.requestRecordPermission() { (allowed: Bool) -> Void in
dispatch_async(dispatch_get_main_queue()) {
if allowed {
// success
} else {
// TBD: Show a message to the user that they need to give permission in settings app to proceed
}
}
}
} catch {
// TBD: Show a message to the user that they need to give permission in settings app to proceed
}
}