title: drawing dashed line using CALayer
body: <p>I was able to draw a dashed box, using the following code:</p>
  
  <pre><code>CAShapeLayer *shapeLayer = [CAShapeLayer layer];
  CGRect shapeRect = CGRectMake(0.0f, 0.0f, 200.0f, 100.0f);
  [shapeLayer setBounds:shapeRect];
  [shapeLayer setPosition:CGPointMake(self.coreImageView_.frameX, self.coreImageView_.frameBottom - self.coreImageView_.frameHeight/2)];
  [shapeLayer setFillColor:[[UIColor clearColor] CGColor]];
  [shapeLayer setStrokeColor:[[UIColor whiteColor] CGColor]];
  [shapeLayer setLineWidth:2.0f];
  [shapeLayer setLineJoin:kCALineJoinRound];
  [shapeLayer setLineDashPattern:
  [NSArray arrayWithObjects:[NSNumber numberWithInt:5],
  [NSNumber numberWithInt:5],
    nil]];
  </code></pre>
  
  <p>Now if I want to just draw a dashed line from point X to point B, how should I modify this code?</p>