         
         for (index, file) in _tones.enumerated() {
           var filePath: String = Bundle.main.path(forResource: "tones/\(toneDir)/\(file)", ofType: "wav")!
-          var fileURL: URL = URL(fileURLWithPath: filePath)!
-          var audioFile = AVAudioFile(forReading: fileURL, error: nil)
-          var audioFileBuffer = AVAudioPCMBuffer(PCMFormat: audioFile.processingFormat, frameCapacity: UInt32(audioFile.length))
-          audioFile.readIntoBuffer(audioFileBuffer, error: nil)
-          var player = AVAudioPlayerNode()
-          engine.attach(player)
-          engine.connect(player, to: mixer, format: audioFile.processingFormat)
-          player.volume = 0.0
-          player.scheduleBuffer(audioFileBuffer, atTime: nil, options:.Loops, completionHandler: nil)
-          players += [player]
-          
-          if format == nil {
-            format = audioFile.processingFormat
+          var fileURL: URL = URL(fileURLWithPath: filePath)
+          do {
+            let audioFile = try AVAudioFile(forReading: fileURL)
+            let audioFileBuffer = AVAudioPCMBuffer(pcmFormat: audioFile.processingFormat, frameCapacity: UInt32(audioFile.length))
+            audioFile.readIntoBuffer(audioFileBuffer, frameCount: nil)
+            let player = AVAudioPlayerNode()
+            engine.attach(player)
+            engine.connect(player, to: mixer, format: audioFile.processingFormat)
+            player.volume = 0.0
+            player.scheduleBuffer(audioFileBuffer, at: nil, options:.loops, completionHandler: nil)
+            players += [player]
+            
+            if format == nil {
+              format = audioFile.processingFormat
+            }
+          }
+          catch {
+            print("Cannot load audioFile !")
           }
         }
       }

  
  @IBAction func tapToneName(_ sender: UIButton) {
    let initial: Int = toneDirs.index(of: toneNameBtn.titleLabel!.text!)!
    ActionSheetStringPicker.showPickerWithTitle("Tone", rows: toneDirs, initialSelection: initial, doneBlock: {
      picker, value, index in
        let key: String = "\(index)"
        self.initPlayers(key)
        return
    }, cancelBlock: { ActionStringCancelBlock in return }, origin: sender)
  }
  
  // AVAudioPlayerNode の生成やAudioFileの設定

            let _slider: UISlider = beaconUI?[1] as! UISlider
            
            if _switch.isOn {
              if accuracy_min == nil || Float(_beacon.accuracy) < accuracy_min! {
                accuracy_min = Float(_beacon.accuracy)
                nearestBeacon = beaconName
              }
