iOS Charts - single values not showing Swift - swift

Question

When I have multiple points in an array for a line on a line graph, everything shows perfectly.
But when there is only one point, the dot does not show. I dont know why?
the delegate is being set elsewhere, but this doesnt seem to be the issue.
The below examples shows Test 2 and Test exercise. The first image is where each has one value, the second they each have 2.
heres my code
func startChart(){
chart.dragEnabled = true
chart.legend.form = .circle
chart.drawGridBackgroundEnabled = false
let xaxis = chart.xAxis
xaxis.valueFormatter = axisFormatDelegate
xaxis.labelCount = dataSets.count
xaxis.labelPosition = .bottom
xaxis.granularityEnabled = true
xaxis.granularity = 1.0
xaxis.avoidFirstLastClippingEnabled = true
xaxis.forceLabelsEnabled = true
let rightAxis = chart.rightAxis
rightAxis.enabled = false
rightAxis.axisMinimum = 0
let leftAxis = chart.leftAxis
leftAxis.drawGridLinesEnabled = true
leftAxis.axisMinimum = 0
let chartData = LineChartData(dataSets: dataSets)
chart.data = chartData
}
If I add
chart.setVisibleXRangeMinimum(myMinDate)
the value will show correctly. however it squashes the value to the left and overlaps 2 x value dates

Answer 1

The only way I could get around this was to add an additional invisible line.
I created a clear line that started the day before and ended the day after my single values.
As long as there is a line on the chart that goes from one point to another, the other single values show.
var singleValue = false
for i in 0...(dataSets.count - 1) {
if dataSets[i].values.count > 1{
singleValue = true
}
}
var data = dataSets
if singleValue == false {
let minNS = Calendar.current.date(byAdding: .day, value: -1, to: minNSDate as! Date)
let maxNS = Calendar.current.date(byAdding: .day, value: 1, to: maxNSDate as! Date)
var dataEntries: [ChartDataEntry] = []
let dataEntry1 = ChartDataEntry(x:Double(String(format: "%.2f",Double((minNS?.timeIntervalSince1970)!)))!,y:00.00)
let dataEntry2 = ChartDataEntry(x:Double(String(format: "%.2f",Double((maxNS?.timeIntervalSince1970)!)))!,y:00.00)
dataEntries.append(dataEntry1)
dataEntries.append(dataEntry2)
let set = LineChartDataSet(values: dataEntries, label: "")
set.setCircleColor(UIColor.clear)
set.circleHoleColor = UIColor.clear
set.setColor(UIColor.white, alpha: 0.0)
set.drawValuesEnabled = false
data.append(set)
}
chart.chartDescription?.text = ""
let chartData = LineChartData(dataSets: data)
chart.data = chartData

Answer 2

I think I found a better solution. Single point is not enough to draw a line (you need at least two points) so LineChartView can't render your data. You can fix that by replace LineChartView with CombinedChartView. CombinedChartView give a possibility to mix different types of data on one chart. You can check how many data entires do you have and decide which type of DataSet will be proper.
Code example:
if dataEntry.count == 1 {
let scatterDataSet = ScatterChartDataSet(values: dataEntry, label: title)
scatterDataSet.setColor(UIColor.pmd_darkBlue)
scatterDataSet.setScatterShape(.circle)
scatterDataSet.drawValuesEnabled = false
combinedChartData.scatterData = ScatterChartData(dataSets: [scatterDataSet])
}
else {
let lineDataSet = LineChartDataSet(values: dataEntry, label: title)
lineDataSet.setColor(UIColor.pmd_darkBlue)
lineDataSet.lineWidth = 3.0
lineDataSet.drawCirclesEnabled = false
lineDataSet.drawValuesEnabled = false
combinedChartData.lineData = LineChartData(dataSets: [lineDataSet])
}
combinedChart.data = combinedChartData
You can also combine two and more types DataSets in one chart.
Important
Don't forget to add this line:
combinedChart.drawOrder = [DrawOrder.line.rawValue, DrawOrder.scatter.rawValue]
You must to write types of data types you use otherwise data will not render.