title: CPTScatterPlot connect point with skip some data point
body: <p>For example, from 09:00am to 09:05:am<br>
  Ideally, I got 6 points from server for my plot.</p>
  
  <pre><code>- (NSUInteger)numberOfRecordsForPlot:(CPTPlot *)plot {
     return 6;
  }
  </code></pre>
  
  <p>dataSource</p>
  
  <pre><code>Index Time  Price    
  
  0     09:00 84.2
  1     09:01 84.5
  2     09:02 84.1
  3     09:03 84.0
  4     09:04 84.1
  5     09:05 84.0
  </code></pre>
  
  <p>But, In fact, Server will response data source like this</p>
  
  <pre><code>Index Time  Price    
  0     09:00 84.2
  1     09:01 84.5
  2     09:02 nil
  3     09:03 nil
  4     09:04 84.1
  5     09:05 84.0
  </code></pre>
  
  <p>I return 6 for numberOfRecordsForPlot<br>
  And nil for numberForPlot index 2 and 3<br>
  I will get plot like this
    <a href="https://i.stack.imgur.com/NPVWE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NPVWE.png" alt="enter image description here"></a>
  My question is 
  if index 2 and index 3 no data<br>
  How do I connect index 1 to index 4 with a straight line<br>
  i.e. connect (1, 84.5) to (4, 84.1) using a straight line</p>