To make the line smoother, either give it more data points or make a curved plot.
plot.interpolation = CPTScatterPlotInterpolationCurved;
If you know the range of data values, just set the xRange
directly. Remember to set the location to the min
value and the length to (max - min)
. You can also have the graph scale the plot space for you.
[plotSpace scaleToFitPlots:[graph allPlots]];