iOS Chart Horizontal Bar Chart not showing bar values

Question

I am using iOS charts (V3.3) to draw a horizontal bar chart for player performance statistics for a sports app. I want the bar value to be shown next to the bar in each case. I can make this happen provided that the player has both negative and positive performance points, but if the player only has positive performance points, no values are shown.

I have the BarChartView in its own class, and am using this code

import Charts

class PlayerPerformanceBarChart: HorizontalBarChartView, IValueFormatter {

override init(frame: CGRect) {
    super.init(frame: frame)
}

required init(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

func setChart(pf: [PerformanceStat]) {
    noDataTextColor = Style.labelText
    noDataText = gf.getLiteral("noPerformanceData")
    isUserInteractionEnabled = false
    legend.enabled = false
    leftAxis.enabled = false
    rightAxis.enabled = false
    chartDescription?.text = nil
    drawValueAboveBarEnabled = true

    // Data
    var dataEntries: [BarChartDataEntry] = []
    var labels: [String] = []
    for i in 0..<pf.count {
        dataEntries.append(BarChartDataEntry(x: Double(i), y: Double(pf[i].playerPoints)))
        labels.append(pf[i].playerAction)
    }
    let chartDataSet = BarChartDataSet(entries: dataEntries, label: nil)
    chartDataSet.colors = ChartColorTemplates.joyful()
    chartDataSet.valueFormatter = self
    let chartData = BarChartData(dataSets: [chartDataSet])
    chartData.setDrawValues(true)
    
    // X Axis - which for a Horizontal Bar Chart is actually the vertical (Y) axis - I know, crazy but true!!
    let xaxis = self.xAxis
    xaxis.drawGridLinesEnabled = false
    xaxis.labelPosition = .bottom
    xaxis.labelCount = pf.count
    xaxis.axisMinimum = -1
    xaxis.resetCustomAxisMin()
    xaxis.centerAxisLabelsEnabled = false
    xaxis.granularity = 1
    xaxis.granularityEnabled = true
    xaxis.labelTextColor = Style.chartText
    xaxis.valueFormatter = IndexAxisValueFormatter(values: labels)
    clipValuesToContentEnabled = true

    //Chart Format and Display
    data = chartData
}

func stringForValue(_ value: Double, entry: ChartDataEntry, dataSetIndex: Int, viewPortHandler: ViewPortHandler?) -> String {
    return Int(value).description
}

}

The function setChart is called by the containing view (which is a UIScrollView)

It is only a single data set, so no grouping. I cannot find out why the values would not show when there are no negative values to display. Looking at the Charts code, it is something to do with the position of the bar being outside the bounds of the viewport handler, but I cannot see why that would be the case.

Any help would be appreciated

Lilya Lilya · Accepted Answer · 2020-08-14T09:49:09

It's better to create a separate class responsible for the values formatting.

import UIKit
import Charts

class ValueFormatter: NSObject, IAxisValueFormatter {
    func stringForValue(_ value: Double, axis: AxisBase?) -> String {
       /// your code for formatting the values
    }
}

And you should assign the custom class as your value formatter:

xAxis.valueFormatter = ValueFormatter()

Aside from that, please, take a look at this wonderful tutorial on how to set the custom values for the labels: https://medium.com/@spmandrus/ios-charts-custom-y-axis-values-e03cac8850c

iOS Chart Horizontal Bar Chart not showing bar values

1 Answers