I am getting partial success by doing the following:
// add the chart view to tempView that is positioned off screen
UIGraphicsBeginImageContextWithOptions(chartView.bounds.size, YES, 0.0);
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
And I get a chart output with gridlines, x,y labels and chart labels..........but the seires lines are missing????
See attached image
I have a real need to cycle all charts in my app to export the chart as an image, but if for exapmple I have 8 charts then I create each in turn off screen, export, remove and move onto next....