iOS speaker output format (iPhone)

I want to playback audio data received from the network. My incoming audio PCM data are in the format Int16, 1 channel, sample rate 8000, 160 bytes/package

Now I'm not sure, which audio format iOS is supporting on the speaker side? IMHO I have to work with Float32 and the sample rate 44.100 / 48000 is that right?

So I think I have to convert my Int16 linear PCM data to Float32. Maybe I have also tu resample the data from 8k to 48k,

I'm not sure (maybe the hardware does it).

Could someone help me? Here is my current code, where I build the AVAudioPCMBuffer.

func convertInt16ToFloat32(_ data: [Int16]) -> AVAudioPCMBuffer {
  let audioBuffer = AVAudioPCMBuffer(pcmFormat: outputFormat!, frameCapacity: 160)!

  // Each real data of the array input is reduced to the interval [-1, 1]
  for i in 0..<data.count {
     // Convert the buffer to floats. (before resampling)
     let div: Float32 = (1.0 / 32768.0)
     let floatKiller = div * Float32(i)

     audioBuffer.floatChannelData?.pointee[i] = floatKiller
  }

  audioBuffer.frameLength = audioBuffer.frameCapacity
  return audioBuffer
}

And on the other side I play back the created AVAudioPCMBuffer in my AVAudioEngine.

func playFromNetwork(data: [Int16]) {
  // data: linear data PCM-Int16, sample rate 8000, 160 bytes
  let audio = convertInt16ToFloat32(data)
  // playback converted data on AVAudioPlayerNode
  self.playerNode!.scheduleBuffer(audio, completionHandler: nil)
  Logger.Audio.log("Play audio data .....")
}

Here is my setup for AVAudioEngine:

func initAudio() {
  try! AVAudioSession.sharedInstance().setActive(true)
  try! AVAudioSession.sharedInstance().setCategory(.playback)
  let outputFormat = AVAudioFormat.init(commonFormat: AVAudioCommonFormat.pcmFormatFloat32, sampleRate: 8000, channels: 1, interleaved: false)  

  engine = AVAudioEngine()
  playerNode = AVAudioPlayerNode()

  engine!.attach(playerNode!)
  engine!.connect(playerNode!, to: engine!.mainMixerNode, format: outputFormat)
  engine!.prepare()

  try! engine!.start()
  playerNode!.play()
}