ios Charts 3.0 - Align x labels (dates) with plots

OK, got it!

You've got to define a reference time Interval (the "0" for the x axis). And then calculate the additional time interval for each x value.

The ChartXAxisFormatter becomes:

import Foundationimport Chartsclass ChartXAxisFormatter: NSObject {    fileprivate var dateFormatter: DateFormatter?    fileprivate var referenceTimeInterval: TimeInterval?    convenience init(referenceTimeInterval: TimeInterval, dateFormatter: DateFormatter) {        self.init()        self.referenceTimeInterval = referenceTimeInterval        self.dateFormatter = dateFormatter    }}extension ChartXAxisFormatter: IAxisValueFormatter {    func stringForValue(_ value: Double, axis: AxisBase?) -> String {        guard let dateFormatter = dateFormatter,        let referenceTimeInterval = referenceTimeInterval        else {            return ""        }        let date = Date(timeIntervalSince1970: value * 3600 * 24 + referenceTimeInterval)        return dateFormatter.string(from: date)    }}

And, then, when I create my data entries, it works like so:

// (objects is defined as an array of struct with date and value)// Define the reference time intervalvar referenceTimeInterval: TimeInterval = 0if let minTimeInterval = (objects.map { $0.date.timeIntervalSince1970 }).min() {        referenceTimeInterval = minTimeInterval    }    // Define chart xValues formatter    let formatter = DateFormatter()    formatter.dateStyle = .short    formatter.timeStyle = .none    formatter.locale = Locale.current    let xValuesNumberFormatter = ChartXAxisFormatter(referenceTimeInterval: referenceTimeInterval, dateFormatter: formatter)    // Define chart entries    var entries = [ChartDataEntry]()    for object in objects {        let timeInterval = object.date.timeIntervalSince1970        let xValue = (timeInterval - referenceTimeInterval) / (3600 * 24)        let yValue = object.value        let entry = ChartDataEntry(x: xValue, y: yValue)        entries.append(entry)    }// Pass these entries and the formatter to the Chart ...

The result is much nicer (I removed cubic by the way):

If you exactly know how many labels you need in the x-axis,you can write this code to solve it.For example,If I need seven labels to appear on the x-axis,Then this should be enough.The reason is the chart library is not properly calculating the intervals between the two x-axis points and hence the plot-label mismatch.When we force the library to plot against the given number of labels,The issue seems to be gone.

 let xAxis = chart.xAxis xAxis.centerAxisLabelsEnabled = false xAxis.setLabelCount(7, force: true) //enter the number of labels here

override func viewDidLoad() {    super.viewDidLoad()    self.lineChart.delegate = self    self.lineChart.chartDescription?.textColor = UIColor.white    let months = ["Jan" , "Feb", "Mar"]    let dollars1 = [1453.0,2352,5431]    setChart(months, values: dollars1)}func setChart(_ dataPoints: [String], values: [Double]) {    var dataEntries: [ChartDataEntry] = []    for i in 0 ..< dataPoints.count {        dataEntries.append(ChartDataEntry(x: Double(i), y: values[i]))    }    let lineChartDataSet = LineChartDataSet(values: dataEntries, label: nil)    lineChartDataSet.axisDependency = .left    lineChartDataSet.setColor(UIColor.black)    lineChartDataSet.setCircleColor(UIColor.black) // our circle will be dark red    lineChartDataSet.lineWidth = 1.0    lineChartDataSet.circleRadius = 3.0 // the radius of the node circle    lineChartDataSet.fillAlpha = 1    lineChartDataSet.fillColor = UIColor.black    lineChartDataSet.highlightColor = UIColor.white    lineChartDataSet.drawCircleHoleEnabled = true    var dataSets = [LineChartDataSet]()    dataSets.append(lineChartDataSet)    let lineChartData = LineChartData(dataSets: dataSets)    lineChart.data = lineCh[![enter image description here][1]][1]artData    lineChart.rightAxis.enabled = false    lineChart.xAxis.drawGridLinesEnabled = false    lineChart.xAxis.labelPosition = .bottom    lineChart.xAxis.valueFormatter = IndexAxisValueFormatter(values: dataPoints)}