How to draw a rectangle,or how to get the last point's CGPoint?

[yumazaki]

I want to draw this rectangle.

I've searched several hours, how to get it or how to draw?

[liuxuan30]

drawing the rect has many options; but I guess you can use ChartMarker and change the coordinates, or you write a new method to draw this;
for the last point - if you can know the lat value's xIndex and it's value, you can convert it into pixels; ChartTransformer's method is doing the job. Take a look at how line dot is drawn; it's in line chart renderer.