title: simulate an elastic animation with UIPangestureRecognizer
body: <p>I'm trying to use <code>UIPangestureRecognizer</code> for simulate an "elastic" effect. I would like drag an UIView around but it should appears anchored in a specific point of his superview.</p>
  
  <p>I tried with this code, decreasing the offeset with a multiplier, but it is linear and the effect is not what i'm looking for.</p>
  
  <pre><code>float percentage = distance / maxDistance;
  float multiplier = (1 - percentage) ;
  CGPoint center = { self.targetView.center.x , self.targetView.center.y +  translation.y * multiplier};  
  [self.targetView setCenter:center];
  [recognizer setTranslation:CGPointZero inView:self.view];
  </code></pre>
  
  <p>I found this repository <a href="https://github.com/warrenm/AHEasing" rel="nofollow">https://github.com/warrenm/AHEasing</a>, but i don't understand how can i use the <code>ExponentialEaseOut</code>.</p>