title: CorePlot : how to drag an image in graph
body: <p>I have added one image to my graph with help of CPTPlotspace annotation.Code is as follows</p>
  
  <pre><code>UIImage *image=[UIImage imageNamed:@"marker.gif"];
  CPTImage *fillimage=[CPTImage imageWithCGImage:image.CGImage];
  CPTBorderedLayer *imageLayer = [[CPTBorderedLayer alloc]init];
  imageLayer.frame=CGRectMake(0, 0, 10, 10);
  imageLayer.fill=[CPTFill fillWithImage:fillimage];  
  CPTPlotSpaceAnnotation *imageannotation  = [[CPTPlotSpaceAnnotation alloc] initWithPlotSpace:graph.defaultPlotSpace anchorPlotPoint:anchorPoint];
  imageannotation.contentLayer = imageLayer;
  [graph.plotAreaFrame.plotArea addAnnotation:imageannotation];
  </code></pre>
  
  <p>Result is given in link below.</p>
  
  <p><a href="http://i.stack.imgur.com/0tPh2.png" rel="nofollow">Result</a></p>
  
  <p><strong>Now,Problem is How can i drag the image (black coloured marker on graph) along the data line?</strong> </p>