Core Plot: How to present popover from a bar selected by the user

Question

What I would like to accomplish

I am using Core Plot (1.1) to draw a bar chart and I would like to present a popover with further details below the bar which has b

Answer 1

The -plotAreaViewPointForPlotPoint: method returns a point in the plot area coordinate system. You need to convert that to the graph's coordinate system:

[graph convertPoint:dataPoint fromLayer:graph.plotAreaFrame.plotArea];

The graph and its hosting view share a coordinate system. If self.view is not the hosting view, you will need to convert the coordinates to its coordinate system from the hosting view.

---

A more complete code sample:

NSDecimal plotPoint[2];
NSNumber *plotXvalue = [self numberForPlot:plot
                                     field:CPTScatterPlotFieldX
                               recordIndex:idx];
plotPoint[CPTCoordinateX] = plotXvalue.decimalValue;

NSNumber *plotYvalue = [self numberForPlot:plot
                                     field:CPTScatterPlotFieldY
                               recordIndex:idx];
plotPoint[CPTCoordinateY] = plotYvalue.decimalValue; 

CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)graph.defaultPlotSpace;

// convert from data coordinates to plot area coordinates
CGPoint dataPoint = [plotSpace plotAreaViewPointForPlotPoint:plotPoint];

// convert from plot area coordinates to graph (and hosting view) coordinates
dataPoint = [graph convertPoint:dataPoint fromLayer:graph.plotAreaFrame.plotArea];

// convert from hosting view coordinates to self.view coordinates (if needed)
dataPoint = [self.view convertPoint:dataPoint fromView:hostingView];

NSLog(@"barWasSelectedAtRecordIndex x: %@, y: %@", plotXvalue, plotYvalue);
NSLog(@"datapoint coordinates tapped: %@", NSStringFromCGPoint(dataPoint));