Core plot objective c : Why gridlines does not show when custom label is used

I'm trying to draw a bar chart with gridlines and custom labels. Unfortunately I can't get it to display both custom label and gridlines. To have gridlines I 开发者_开发问答need to set the axis labelingPolicy to CPTAxisLabelingPolicyAutomatic but this does not show the custom label any more. Is there anything I am doing wrong or is there a correct way to do what I am trying to achieve. Thank you.

When using custom labels, you also have to set the majorTickLocations and/or minorTickLocations. The grid lines are drawn at the corresponding tick locations.