Rendering basic bar chart with core plot in swift

Question

I am trying to render a basic bar chart with this code:

    import UIKit
    import CorePlot

    class BarChart: CPTGraphHostingView, CPTPlotDataSource, CPTPlotDelegate, CPTPlotSpaceDelegate
    {
    let data: [[UInt]] = [
        [30, 40, 100],
        [10, 44, 35]
    ]

    func renderData() {
        let barGraph = CPTXYGraph(frame: self.bounds)
        self.hostedGraph = barGraph
        barGraph.axisSet = nil

        var space: CPTXYPlotSpace = barGraph.defaultPlotSpace as! CPTXYPlotSpace
        barGraph.addPlotSpace(space)
        space.yRange = CPTPlotRange(locationDecimal: CPTDecimalFromFloat(0), lengthDecimal: CPTDecimalFromFloat(50))
        space.xRange = CPTPlotRange(locationDecimal: CPTDecimalFromFloat(0), lengthDecimal: CPTDecimalFromFloat(3))
        space.delegate = self

        var bar = CPTBarPlot(frame: barGraph.bounds)
        bar.dataSource = self
        bar.barWidth = 3

        barGraph.addPlot(bar, toPlotSpace: space)
    }

    func numberForPlot(plot: CPTPlot, field: UInt, recordIndex: UInt ) -> AnyObject? {
        return data[0][Int(idx)]
    }

    func barFillForBarPlot(barPlot: CPTBarPlot, recordIndexRange indexRange: NSRange) -> AnyObject? {
        return CPTFill(color: CPTColor(componentRed: 0, green: 0, blue: 255, alpha: 1))
    }

    func numberOfRecordsForPlot(plot: CPTPlot) -> UInt {
        return 3
    }
    }

This class is associated with a view in storyboard. Unfortunately, I can't manage to display any data (but axis are visible when i remove the line with barGraph.axisSet = nil ). Am I missing something? Thanks!

Answer 1

When using Swift, I would recommend getting the version of Core Plot on the "release-2.0" branch from GitHub. It has some API changes to make working with Swift easier. The biggest one is offering alternatives to the methods and properties that use NSDecimal values, eg, plot ranges. I hope to have release 2.0 done soon after Xcode 7 is final.

There's no need to add the default plot space to the graph; it's already there.

The -numberForPlot:field:recordIndex: function should return the value as an NSNumber . Cast the value when returning it, eg, return data[0][Int(idx)] as NSNumber .