title: Motion/Moving effect with animation on still image
body: <p>I am trying to implement animation in a still image in a user-guided direction, something like this:</p>
  
  <p><strong>Original image</strong></p>
  
  <p><a href="https://i.stack.imgur.com/U0JTq.png" rel="noreferrer"><img src="https://i.stack.imgur.com/U0JTq.png" alt="original image"></a></p>
  
  <p><strong>Expected result</strong></p>
  
  <p><a href="https://i.stack.imgur.com/BSgEC.gif" rel="noreferrer"><img src="https://i.stack.imgur.com/BSgEC.gif" alt="expected result"></a></p>
  
  <p>For this, I have tried the <code>CIBumpDistortionLinear</code> <code>CIFilter</code>. It is animating, but the animation is not exactly like that. </p>
  
  <pre><code>let bumpDistortionLinearParams: [String: AnyObject] = [
      kCIInputImageKey: coreImage!,
      "inputCenter" : CIVector(string: coordStr),
      "inputRadius": 300.0 as AnyObject,
      "inputAngle" : 90.0 as AnyObject,
      "inputScale" : 0.1 as AnyObject
  ]
  
  let bumpDistortionLinear = CIFilter(name: "CIBumpDistortionLinear", parameters: bumpDistortionLinearParams)
  </code></pre>