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swiftios-charts

Does the legend limit the number of titles?

I am using iso-charts to try and draw a pie chart in an iOS app.

No matter what I try, I can't seem to get the full number of titles to draw in the legend.

I have my data set up as:

ages = ["18-", "25-", "35-", "45-", "55-", "65-", "75+"]
agePercentages = [10.0, 20.0, 30.0, 5.0, 10.0, 45.0, 120.0]

My code to setup the pieChart as:

func setPieDefaults(myPieChart: PieChartView) -> PieChartView {

    myPieChart.frame = CGRectMake(0, 0, UIScreen.mainScreen().bounds.size.width, UIScreen.mainScreen().bounds.size.width*0.5)
    myPieChart.usePercentValuesEnabled = true
    myPieChart.holeTransparent = true
    myPieChart.holeColor = UIColor.darkPurpleColor()
    myPieChart.backgroundColor = UIColor.darkPurpleColor()
    myPieChart.rotationAngle = 0.0
    myPieChart.rotationEnabled = true
    myPieChart.centerTextFont = UIFont(name: "HelveticaNeue-Bold", size:20)!
    myPieChart.descriptionText = ""
    myPieChart.centerText = "%"
    myPieChart.centerTextColor = UIColor.whiteColor()
    myPieChart.drawHoleEnabled = true
    myPieChart.noDataText = "Loading Data ..."
    let legend = myPieChart.legend
    legend.font = UIFont(name: "Arial", size: 11)!
    legend.textColor = UIColor.whiteColor()
    legend.position = .RightOfChart
    legend.form = .Circle

    return myPieChart
}

And ..

func setChart(dataPoints: [String], values: [Double], myPieView: PieChartView) {

    var dataEntries: [ChartDataEntry] = []

    for i in 0..<dataPoints.count {
        let dataEntry = ChartDataEntry(value: values[i], xIndex: i)
        dataEntries.append(dataEntry)
    }

    var colors = [UIColor]()
    switch myPieView {
    case genderPieChartView:
        colors = [UIColor.blueColor(), UIColor.pinkColor()]
    default:
        colors = ChartColorTemplates.colorful()
    }

    let pieChartDataSet = PieChartDataSet(yVals: dataEntries, label: nil)
    pieChartDataSet.sliceSpace = 3.0
    pieChartDataSet.colors = colors

    let pieChartData = PieChartData(xVals: dataPoints, dataSet: pieChartDataSet)
    myPieView.animate(xAxisDuration: 2, yAxisDuration: 2)

    let pFormatter = NSNumberFormatter()
    pFormatter.numberStyle = .PercentStyle
    pFormatter.maximumFractionDigits = 0
    pFormatter.percentSymbol = ""
    pFormatter.multiplier = 1
    pieChartData.setValueFormatter(pFormatter)
    pieChartData.setValueFont(UIFont(name: "HelveticaNeue-Bold", size: 11)!)
    pieChartData.setValueTextColor(UIColor.whiteColor())

    myPieView.data = pieChartData
    myPieView.drawSliceTextEnabled = false

}

But it won't print any more than 5 of the labels. It's returning the pie-slices perfectly. But not the labels in the legend.

enter image description here

Am I doing something wrong? Thanks in advance for letting me know.

Solution

  • Solved.

    In reading the framework docs for the Android version a little better:

    The number of entries the automatically generated legend contains depends on the number of different colors (across all DataSet objects) as well as on the DataSet labels. The labels of the Legend depend on the labels set for the used DataSet objects in the chart. If no labels for the DataSet objects have been specified, the chart will automatically generate them. If multiple colors are used for one DataSet, those colors are grouped and only described by one label.

    I realised I needed to increase the number of colours in the ChartColorTemplate.colorful() definition to match the number of labels I was trying to use. The current example code comes with only 5 colours defined.

    public class func colorful () -> [UIColor]
{
    return [
        UIColor(red: 193/255.0, green: 37/255.0, blue: 82/255.0, alpha: 1.0),
        UIColor(red: 255/255.0, green: 102/255.0, blue: 0/255.0, alpha: 1.0),
        UIColor(red: 245/255.0, green: 199/255.0, blue: 0/255.0, alpha: 1.0),
        UIColor(red: 106/255.0, green: 150/255.0, blue: 31/255.0, alpha: 1.0),
        UIColor(red: 179/255.0, green: 100/255.0, blue: 53/255.0, alpha: 1.0),
        UIColor(red: 200/255.0, green: 100/255.0, blue: 53/255.0, alpha: 1.0), // added colour
        UIColor(red: 150/255.0, green: 150/255.0, blue: 70/255.0, alpha: 1.0), // added colour
        UIColor(red: 84/255.0, green: 78/255.0, blue: 53/255.0, alpha: 1.0), // added colour
    ]
}

    If you have the same problem, then define a lot more colours to meet the needs of the maximum number of labels needed. This will also solve a problem if you try and word-wrap the legend (which I was also facing).