title: UIImage.animatedImageNamed returns nil
body: <p>I am trying to load a sequence of images in an animation. I am keeping those images in the assets (spinner1 to spinner42) and so I am using:</p>
  
  <pre><code>@IBOutlet weak var imageView: WKInterfaceImage!
      override func didAppear() {
          super.didAppear()
          let animatedImage = UIImage.animatedImageNamed("spinner", duration: 10)
          imageView.setImage(animatedImage)
      }
  }
  </code></pre>
  
  <p>But I am always returned a nil image. If I set spinner1, I se the image but no animation. What is the proper way to animate an image on WatchKit?</p>