While parsing JSON data, I get different result, from same url - ios

Question

Problem Statement: Every time whenever I refresh viewController, then I get different values.
Required Solution: Whenever I refresh, it should fetch same values.
Coding Stuff:
Below I have get values from JSON parsing via url. After fetching values, it pass to the 'setChart() function as a parameter.'
override func viewDidLoad()
{
super.viewDidLoad()
var completedCalls = 0
for i in 0..<strDates.count {
Alamofire.request("http://api.fixer.io/\(strDates[i])?base=USD").responseJSON { response in
if let arr = response.result.value as? [String:AnyObject]
{
completedCalls += 1
let inrc = (arr["rates"]?["INR"] as? Double)!
print(inrc)
self.sValues.append(inc)
print(sValues)
//It prints values here.
if completedCalls = strDates.count {
DispatchQueue.main {
setChart(dataPoints: strDates, values: sValues)
}
}
}
}
}
setChart() Function
func setChart(dataPoints: [String], values: [Double]) {
barChartView.noDataText = "You need to provide data for the chart."
for i in 0..<dataPoints.count {
let dataEntry = BarChartDataEntry(x: Double(i), yValues: [values[i]])
dataEntries.append(dataEntry)
}
let chartDataSet = BarChartDataSet(values: dataEntries, label: "INR Rates(₹)/$")
let chartData = BarChartData(dataSet: chartDataSet)
barChartView.data = chartData
barChartView.leftAxis.axisMinimum = 65
barChartView.leftAxis.axisMaximum = 70
barChartView.xAxis.labelPosition = .bottom
barChartView.rightAxis.enabled = false
barChartView.data?.setDrawValues(false)
}
}

Answer 1

You're issuing a sequence of asynchronous requests, but you have no assurances the order in which they'll complete.
I would suggest capturing the results in a dictionary, with the strDates as the key. Then you can extract them in the correct order when presenting the results.
So, I'm assuming that assuming that sValues is defined as:
var sValues = [Double]()
Change that to:
var sValues = [String: Double]()
And then, rather than:
self.sValues.append(inc)
You would do:
self.sValues[strDates[i]] = inc
Then, in your charting code, iterate through strDates array, and look up the sValues using those date strings.