title: Value of type 'AVCapturePhotoSettings' has no member 'availablePreviewPhotoPixelFormatTypes
body: <pre><code>@objc func launchCoreML() {
      let settings = AVCapturePhotoSettings()
      let previewPixelType = settings.availablePreviewPhotoPixelFormatTypes.first
      let previewFormat = [
          kCVPixelBufferPixelFormatTypeKey as String: previewPixelType, 
          kCVPixelBufferWidthKey as String: 160, 
          kCVPixelBufferHeightKey as String: 160
      ] as [String : Any]
  
      settings.previewPhotoFormat = previewFormat
      cameraOutput.capturePhoto(with: settings, delegate: self)
  }
  </code></pre>
  
  <p>I have an error saying:</p>
  
  <blockquote>
    <p>Value of type 'AVCapturePhotoSettings' has no member
    'availablePreviewPhotoPixelFormat'.</p>
  </blockquote>
  
  <p>I'm using the beta version of Xcode 9. </p>