Trying to enter Date/String in ChartDataEntry

Question

I am trying to add a Date/String as the xAxis labels in Charts (needs to have equal space in between labels)

I am doing below but the x in the constructor only expects a double.

Any idea?

for i in 0..<self.grahEntries.count {
     let x1 = self.grahEntries[i].x
     let dateFormatter = DateFormatter()
     dateFormatter.dateFormat = "YYY-MM-DD HH:mm:ss"
     let date = dateFormatter.date(from: x1)
     print(date)
     let dataEntry = ChartDataEntry(x: date, y: self.grahEntries[i].y)//HERE IS MY PROBLEM!! xAxis is only double
     dataEntries.append(dataEntry)
}

 let line1 = LineChartDataSet(values: dataEntries, label: "Units Consumed")
    line1.colors = [NSUIColor.blue]
    line1.mode = .cubicBezier
    line1.cubicIntensity = 0.2


    let gradient = getGradientFilling()
    line1.fill = Fill.fillWithLinearGradient(gradient, angle: 90.0)
    line1.drawFilledEnabled = true

    let data = LineChartData()
    data.addDataSet(line1)
    mChart.data = data
    mChart.setScaleEnabled(false)
    mChart.animate(xAxisDuration: 1.5)

    mChart.xAxis.valueFormatter = DateAxisValueFormatter()
    mChart.xAxis.granularity = 1.0


    mChart.drawGridBackgroundEnabled = false
    mChart.xAxis.drawAxisLineEnabled = false
    mChart.xAxis.drawGridLinesEnabled = false
    mChart.leftAxis.drawAxisLineEnabled = true
    mChart.leftAxis.drawGridLinesEnabled = true
    mChart.rightAxis.drawAxisLineEnabled = false
    mChart.rightAxis.drawGridLinesEnabled = false
    mChart.legend.enabled = false
    mChart.xAxis.enabled = true
    mChart.leftAxis.enabled = true
    mChart.rightAxis.enabled = false

    mChart.xAxis.labelPosition = .bottom

    mChart.xAxis.drawLabelsEnabled = true
    mChart.xAxis.drawLimitLinesBehindDataEnabled = true
    mChart.xAxis.avoidFirstLastClippingEnabled = true

UPDATE :

I did as @ces said its spreading them accurately but I still cant see labels. I updated my code above to show table

Answer 1

If you want the data to be spaced evenly (i.e. not representing an accurate timeline) then the answer is simpler.

Change your for loop to

var dates: [String] = []
for i in 0..<self.grahEntries.count {
     let x1 = self.grahEntries[i].x
     let dateFormatter = DateFormatter()
     dateFormatter.dateFormat = "YYY-MM-DD HH:mm:ss"
     let date = dateFormatter.date(from: x1)
     dates.append(date)
     let dataEntry = ChartDataEntry(x: Double(i), y: self.grahEntries[i].y)
     dataEntries.append(dataEntry)
}

and change

mChart.xAxis.valueFormatter = DateAxisValueFormatter(dates)

Then change DataAxisValueFormatter to accept an array of strings in the constructor and store them. Change

func stringForValue(_ value: Double, axis: AxisBase?) -> String
{
    let i = Int(value)
    return dates[i]
}