How to change the xAxis labels iOS Charts (Swift 2.3)

Question

I'm trying to create a line chart that has data from the last year. I want to make the labels on the xAxis of the chart represent the months from the last year, which seems to be done easily enough in this tutorial: https://www.codebeaulieu.com/96/How-to-create-a-Combined-Bar-and-Line-chart-using-ios-charts. However, this line of code from the tutorial:

let data: LineChartData = LineChartData(xVals: months, dataSets: dataSets)

where "months" represents an array of strings, is not available after the chart's update to Swift 2.3. The only constructors available for LineChartData are these two:

LineChartData(dataSets: <[IChartDataSet]?>)
LineChartData(dataSet: IChartDataSet?)

so it appears that the option for changing the xVals has disappeared after the update. Was this option moved somewhere else? Or has it been completely removed from iOS Charts?

You can find the solution in below link [link](http://stackoverflow.com/questions/39049188/how-to-add-strings-on-x-axis-in-ios-charts) — Lun, Sep 24 '16 at 10:17

score 3 · Answer 1 · answered Mar 09 '17 at 19:49

After giving up for a while, I finally found the solution. You have to make an IAxisValueFormatter and implement the stringForValue function. For example, I wanted to format my graph to display the last 12 months based on the current month. Here is my value formatter:

import UIKit
import Charts

class MonthNumberFormatter: NSObject, IAxisValueFormatter {

    private let months = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]
    private var startMonthIndex:Int!

    convenience init(startMonthIndex: Int){
        self.init()
        self.startMonthIndex = startMonthIndex
    }

    private func getMonth(index: Int) -> Int{
        return (index % months.count)
    }

    func stringForValue(_ value: Double, axis: AxisBase?) -> String{
        let monthIndex:Int = self.getMonth(index: Int(value) + self.startMonthIndex)
        let month = months[monthIndex]
        return month
    }
}

Then in your chart class --> to get the current month:

func getCurrentMonth()->Int? {
    let todayDate = Date()
    let myCalendar = NSCalendar(calendarIdentifier: .gregorian)
    let myComponents = myCalendar?.components(.month, from: todayDate)
    let month = myComponents?.month
    return month
}

Now set the values on the graph

let xAxis = self.chartView.xAxis
let currentMonth = getCurrentMonth()
xAxis.valueFormatter = MonthNumberFormatter(startMonthIndex: currentMonth!)

How to change the xAxis labels iOS Charts (Swift 2.3)

1 Answers1