title: Using core plot for iPhone, drawing date on x axis
body: <p>I have available an array of dictionary that contains <code>NSDate</code> and <code>NSNumber</code> values. I wanted to plot date on X axis.
  For plotting I need to supply xRanges to plot with some decimal values. I don't understand how can I supply <code>NSDate</code> values to xRange (low and length).</p>
  
  <p>And  what should be there in this method:</p>
  
  <pre><code>-(NSNumber *)numberForPlot:(CPPlot *)plot field:(NSUInteger)fieldEnum recordIndex:(NSUInteger)index
  </code></pre>
  
  <p>I mean how my date value will be returned as <code>NSNumber</code>? I think I should use some interval over there, but what should be the exact conversion?
  Can any one explain me what are the exact requirement to plot the date on xAxis?</p>
  
  <p>I am plotting my plot in half of the view.</p>