Minor grid lines

Has anyone used Charts 3.x to successfully draw minor grid lines in between labels?

I see a couple approaches to accomplish this - one is to use the transformer class to draw custom subviews at the in-between points. When I do this, however, the gridlines appear on top of the data set entries (even if I send them to the back of the view hierarchy) which is undesirable.

The other approach would be a custom formatter that generates empty string labels on odd-numbered indices, which doesn't seem particularly elegant.

What do you think? Would one approach be preferable to the others based on current/future API? (or another approach that I am missing? some core graphics + chart view delegate method?)

Start by reviewing the Charts 3.x transformer and custom formatter approaches mentioned in the issue, then inspect chart-view delegate and Core Graphics drawing options. The issue does not name files or tests; completion would require choosing and documenting or implementing an API-supported way to draw minor grid lines beneath data entries.

Written by the indexing model from the issue text.