 import QuartzCore
 
 @objc public protocol RecorderDelegate: AVAudioRecorderDelegate {
-  func audioMeterDidUpdate(dB: Float)
+  optional func audioMeterDidUpdate(dB: Float)
 }
 
 public class Recording : NSObject {


    recorder.prepareToRecord()
    recorder.delegate = delegate
    recorder.meteringEnabled = meteringEnabled
  }

  public func record() throws {


    let dB = recorder.averagePowerForChannel(0)

    delegate?.audioMeterDidUpdate?(dB)
  }

  private func startMetering() {
