Swift - iOS Charts - Two LineChart views using Two datasets in one ViewController - swift

Question

I have an app where I'm getting some data from Firebase by days and I'm trying to display each day's data in a separate chart, using iOS Charts, but it crashes with an error 'fatal error: Index out of range'. Below is my code:
func setChart(dataPoints: [String], values: [Double]) {
var dataEntries: [ChartDataEntry] = []
for i in 0..<dataPoints.count {
let dataEntry = ChartDataEntry(value: values[i], xIndex: i)
dataEntries.append(dataEntry)
}
let lineChartDataSet = LineChartDataSet(yVals: dataEntries, label: "Units Sold")
let lineChartData = LineChartData(xVals: dataPoints, dataSet: lineChartDataSet)
firstDayChart.data = lineChartData
}
func setChart2(dataPoints: [String], values: [Double]) {
var dataEntries: [ChartDataEntry] = []
for i in 0..<dataPoints.count {
let dataEntry = ChartDataEntry(value: values[i], xIndex: i)
dataEntries.append(dataEntry)
}
let lineChartDataSet = LineChartDataSet(yVals: dataEntries, label: "Units Sold")
let lineChartData = LineChartData(xVals: dataPoints, dataSet: lineChartDataSet)
secondDayChart.data = lineChartData
}
//BUTTON
#IBAction func getResults(sender: UIButton) {
let doubleArray = BGdataOutsideDay1.map { Double($0)!}
// print(doubleArray)
// var newArray:[Double] = []
self.doublesArrayDay1 = doubleArray
if doublesArrayDay1.count != 0 {
let bgAvg = doubleArray.reduce(0, combine: +) / Double(doubleArray.count)
let highest = doubleArray.maxElement()
let lowest = doubleArray.minElement()
self.bgHighestDay1 = String(format: "%.1f", highest!)
self.bgAvgDay1 = String(format: "%.1f", bgAvg)
self.bgLowestDay1 = String(format: "%.1f", lowest!)
self.firstDayHighest.text = self.bgHighestDay1! + " " + "\(self.units!)"
self.firstDayAvg.text = self.bgAvgDay1! + " " + "\(self.units!)"
self.firstDayLowest.text = self.bgLowestDay1! + " " + "\(self.units!)"
} else {
self.firstDayHighest.text = "0" + " " + "\(self.units!)"
self.firstDayAvg.text = "0" + " " + "\(self.units!)"
self.firstDayLowest.text = "0" + " " + "\(self.units!)"
}
let doubleArray2 = BGdataOutsideDay2.map { Double($0)!}
// print(doubleArray)
// var newArray:[Double] = []
self.doublesArrayDay2 = doubleArray
if doublesArrayDay2.count != 0 {
let bgAvg2 = doubleArray2.reduce(0, combine: +) / Double(doubleArray.count)
let highest2 = doubleArray2.maxElement()
let lowest2 = doubleArray2.minElement()
self.bgHighestDay2 = String(format: "%.1f", highest2!)
self.bgAvgDay2 = String(format: "%.1f", bgAvg2)
self.bgLowestDay2 = String(format: "%.1f", lowest2!)
self.secondDayHighest.text = self.bgHighestDay2! + " " + "\(self.units!)"
self.secondDayAvg.text = self.bgAvgDay2! + " " + "\(self.units!)"
self.secondDayLowest.text = self.bgLowestDay2! + " " + "\(self.units!)"
} else {
self.secondDayHighest.text = "0" + " " + "\(self.units!)"
self.secondDayAvg.text = "0" + " " + "\(self.units!)"
self.secondDayLowest.text = "0" + " " + "\(self.units!)"
setChart(DateOutSideDay1, values: doublesArrayDay1)
setChart(DateOutSideDay2, values: doublesArrayDay2)
}
Any help would be greatly appreciated! Thanks in advance! :)

Answer 1

First of all i think it's weird that you have a set of data points and another set of values, but they aren't the same size? Imo those sets should be the same size since the values represent the data points.
Anywho..
You can fix this issue by replacing let dataEntry = ChartDataEntry(value: values[i], xIndex: i) with let dataEntry = ChartDataEntry(value: i < values.count ? values[i] : 0, xIndex: i)
You can define a default value to be used when there's no value available at that index in the values array, I set it to 0.