CODEWITHSUNDEEP
iosios-charts
user1801745
user1801745

Reputation: 389

Labeling xAxis in ios barchart 3.0

I am trying to put labels in barchart using ios-chart 3.0 with no success. My labels are dinamically showed, are no fixed as months.

let chartDataSet = BarChartDataSet(values: dataEntries, label: "animals")
let chartData = BarChartData(xVals: animalsArray, dataSet: chartDataSet)

The last line shows "Cannot invoke initializer for type 'BarChartData' with an argument list of type '(xVals: [String], dataSet: BarChartDataSet)'"

Upvotes: 1

Views: 629

Answers (1)

cdf1982
cdf1982

Reputation: 813

I struggled a bit with this problem too. If I understand it correctly, starting with iOS-Charts 3.0, you can't pass x and y values at the same time, so most tutorials you find online, written for version 2.x, point you in the wrong direction (you can't use BarChartData(xVals: dataSet:) anymore).

On top of that, the fact that the documentation is Android-only, and that the sample code uses cryptic variable names, doesn't help a beginner like me figure this out from the sample project, but I guess I did, since now I'm able to have custom Strings as labels. Here's how:

  1. Conform your class to the IAxisValueFormatter protocol:

    class ChartsViewController : UIViewController, IAxisValueFormatter {//...}

  1. Add a property to your class for the string labels, and initialize it (either hard-coding its values as in the following example, or by setting them in your viewDidLoad:):

    var labelStrings : Array<String> = ["these", "will", "be", "your", "labels"]

  1. Implement the required stringForValue: method of IAxisValueFormatter:

    func stringForValue(_ value: Double, axis: AxisBase?) -> String { return labelStrings[Int(value) % labelStrings.count]}

  1. In your custom "configure chart" method create an XAxis object, set its valueFormatter to self (so the stringForValue: above is called) and set the chartView.valueFormatter equal as the Axis.valueFormatter:

    let xAxis = XAxis() xAxis.valueFormatter = self barChartView.xAxis.valueFormatter = xAxis.valueFormatter

With the points above, you got the custom labels on the X axis, but of course you still have to set the values for Y; just in case someone else comes here for an answer in the future, here's the code to set those values too:

let yValues = myArrayOfCustomValues.enumerated().map { index, element -> BarChartDataEntry in
    return BarChartDataEntry(x: Double(index), y: element)
}

let chartDataSet = BarChartDataSet(values: yValues, label: "If you want a label; you can also pass nil")

let chartData = BarChartData(dataSet: chartDataSet)

barChartView.data = chartData

Upvotes: 2

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