Cannot record using AVAudioEngine - ios

Question

I'm trying to record some audio using AVAudioEngine, but when I start recording with the methods that I have in my setup class, the app crashes and gives me some error, like the following:
2021-07-15 21:28:27.569564-0400 App[75861:6634462] [avae] AVAEInternal.h:88 required condition is false: [AVAudioEngineGraph.mm:1357:Initialize: (IsFormatSampleRateAndChannelCountValid(outputHWFormat))]
2021-07-15 21:28:27.569679-0400 App[75861:6634462] [avae] AVAudioEngine.mm:167 Engine#0x282ad0de0: could not initialize, error = -10875
2021-07-15 21:28:27.571773-0400 App[75861:6634462] Audio files cannot be non-interleaved. Ignoring setting AVLinearPCMIsNonInterleaved YES.
2021-07-15 21:28:27.575892-0400 App[75861:6634462] [avae] AVAEInternal.h:88 required condition is false: [AVAudioEngineGraph.mm:1357:Initialize: (IsFormatSampleRateAndChannelCountValid(outputHWFormat))]
This is the structure that I'm using to make the recording using AVAudioEngine:
class Recorder {
enum RecordingState {
case recording, paused, stopped
}
private var engine: AVAudioEngine!
private var mixerNode: AVAudioMixerNode!
private var state: RecordingState = .stopped
init() {
setupSession()
setupEngine()
}
fileprivate func setupSession() {
let session = AVAudioSession.sharedInstance()
try? session.setCategory(.record)
try? session.setActive(true, options: .notifyOthersOnDeactivation)
}
fileprivate func setupEngine() {
engine = AVAudioEngine()
mixerNode = AVAudioMixerNode()
mixerNode.volume = 0
engine.attach(mixerNode)
makeConnections()
engine.prepare()
}
fileprivate func makeConnections() {
let inputNode = engine.inputNode
let inputFormat = inputNode.outputFormat(forBus: 0)
engine.connect(inputNode, to: mixerNode, format: inputFormat)
let mainMixerNode = engine.mainMixerNode
let mixerFormat = AVAudioFormat(commonFormat: .pcmFormatFloat32, sampleRate: inputFormat.sampleRate, channels: 1, interleaved: false)
engine.connect(mixerNode, to: mainMixerNode, format: mixerFormat)
}
func startRecording() throws {
let tapNode: AVAudioNode = mixerNode
let format = tapNode.outputFormat(forBus: 0)
let documentURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
let file = try AVAudioFile(forWriting: documentURL.appendingPathComponent("recording.caf"), settings: format.settings)
tapNode.installTap(onBus: 0, bufferSize: 4096, format: format, block: {
(buffer, time) in
try? file.write(from: buffer)
})
try engine.start()
state = .recording
}
func stopRecording() {
mixerNode.removeTap(onBus: 0)
engine.stop()
state = .stopped
}
}
And this is how I'm calling the class to start recording:
let hola = Recorder()
do {
try hola.startRecording()
} catch { }