title: VNClassificationObservation not working?
body: <p>I have been hard at work trying to create a simple computer vision application in swift using CoreML and Vision. I have trained my own Keras network that takes colored images with 64x64 resolution and then tells you which letter of the alphabet it is. When I execute this App on my phone and take an image and hit 'use this image', the code crashes at this piece of code:</p>
  
  <pre><code>//send a request to the network to identify the image
              let request = VNCoreMLRequest(model: model) { (request, error) in
                  guard let results = request.results as? [VNClassificationObservation] else {
                      fatalError("Model failed to load image")
              }
  </code></pre>
  
  <p>I have gotten stuck on this error for the past three hours and hope you guys could help me figure out what is wrong! Below is the rest of the code I used. </p>
  
  <pre><code>class ViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
  
      @IBOutlet weak var imageView: UIImageView!
  
      let imagePicker = UIImagePickerController()
  
      override func viewDidLoad() {
          super.viewDidLoad()
  
          imagePicker.delegate = self
          imagePicker.sourceType = .camera
          imagePicker.allowsEditing = false
  
      }
  
      //function to chose an image from your library or take one with your camera
      func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [String : Any]) {
  
          if let userPickedImage = info[UIImagePickerControllerOriginalImage] as? UIImage {
  
              imageView.image = userPickedImage
  
              //transform the image from UIImage to a CIIMage type
              guard let ciImage = CIImage(image: userPickedImage) else {
                  fatalError("Couldn't transform image to CIImage type")
              }
  
              //call the detect function to pass the new ciImage into the network
              detect(image: ciImage)
  
          }
  
          imagePicker.dismiss(animated: true, completion: nil)
  
      }
  
      //function to classify the image that is taken with the camera or chosen from the library
      func detect(image: CIImage) {
  
          //try to load the model, if not throw an error
          guard let model = try? VNCoreMLModel(for: chars74k().model) else {
              fatalError("Loading coreML model failed")
          }
  
          //send a request to the network to identify the image
          let request = VNCoreMLRequest(model: model) { (request, error) in
              guard let results = request.results as? [VNClassificationObservation] else {
                  fatalError("Model failed to load image")
          }
  
              print(results)
  
      }
          //create handler for image
          let handler = VNImageRequestHandler(ciImage: image)
  
          do{
              try handler.perform([request])
          }
          catch {
              print(error)
          }
  </code></pre>