iOS-charts invert the X axis direction

Question

I have a bar chart built using Daniel Gindi iOS-charts. It represents history data over a period of time. The issue I am having is that the data is being plotted from left-to-right (new data -> old data). I need it to be plotted as right-to-left (old data -> new data). I know that I can reverse the order I input data into BarChartData, but then I have the issue of the chart still being left aligned. It needs to be right aligned. I found a discussion here talking about the issue of inverting the x-axis and how it could be resolved (currently not an included feature of the framework), however I can't figure out what actually needs to be done. Here are examples of what I need:

This is what my chart currently looks like:

This is what I needs it to look like:

My Questions

Is there a way to invert the x-axis?

or

Is there a way to right align the chart?

Here is some of my code and attempts to resolve the issue:

class ViewController: UIViewController {

    @IBOutlet weak var barChartView: BarChartView!

    //...

    func plotChart() {

        // Create history data
        //...

        barChartView.data = chartData  // 'chartData' is the BarChartData() containing all of the history information

        // No efect
        barChartView.legend.direction = .RightToLeft

        // Chart breaks
        barChartView.leftAxis.axisMinValue = 30
        barChartView.leftAxis.axisMaxValue = 0

        // Breaks the ability to zoom
        barChartView.setVisibleXRangeMinimum(CGFloat(40))
        barChartView.setVisibleXRangeMaximum(CGFloat(1))

    }

}

Answer 1

In the chartLegend.swift file there is a variable:

public var direction = ChartLegendDirection.LeftToRight

Try to make the change in that file, it might solve your problem.

Answer 2

This library doesn't support right to left alignment directly.

Refer - https://github.com/danielgindi/Charts/issues/738

You have to implement something on library level to make it trick right to left alignment.

Edited answer

After working some around, i found the solution, hope this will help you out.

Download sample code

import UIKit

class ViewController: UIViewController {


  @IBOutlet weak var barChartView: BarChartView!

        override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        let months = ["7/23/2016", "7/22/2016", "7/21/2016", "7/20/2016", "7/19/2016", "7/18/2016", "7/17/2016"]
        let unitsSold = [0.0, 0.0, 0.0, 0.0, 20.0, 50.0, 30.0]

        setChart(months, values: unitsSold)

    }


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

        var dataEntries: [BarChartDataEntry] = []

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

        let chartDataSet = BarChartDataSet(yVals: dataEntries, label: "")
        let chartData = BarChartData(xVals: dataPoints, dataSet: chartDataSet)
        barChartView.data = chartData

        barChartView.leftAxis.enabled = false
        barChartView.descriptionText = ""
        barChartView.xAxis.labelPosition = .Bottom

    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

Answer 3

Ios charts to support Right to left alignment

Steps:

• enable right axis & disable left axis
• invert the data
• set yaxis dependency while drawing Yaxis chartView.getAxis(YAxis.AxisDependency.right)
• set axis dependency for barChartDataSet as YAxis.AxisDependency.right

You are done

Happy Reading