Than you for contacting the iOS team.
TKChart does not support negative zoom on its axes. I added this suggestion to our feedback portal
where you can follow its status. We will consider implementing such functionality if there is enough interest.
Currently a possible way to show the points on left and right of the chart is to change the axis range which will make the points visible with zoom 0.
I hope this helps. If you need more assistance, do not hesitate to contact us.
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