textForAxis delegate method called multiple times

I'm using a TKChart inside a UIView acting as its delegate and data source.

I want to format the graph's xAxis text labels using the textForAxis delegate method upon graph initialization. Problem is, that method is often called 4 or 5 times AFTER the initialization process (once I changed all the graph's xAxis and yAxis by custom built ones) and I'd like to know what fires it.

 My graph contains numerous dataPoints (2000 to 10 000) so repeating the naming of all xAxis values takes a long time. Any way to track or monitor from where the calls are coming or at least limit the number of ticks for which this method is called upon graph initialization?

 Thanks