swift stacked bar chart

Question

I am using the Charts library in Swift to draw bar charts.

Here is my code:

class barChartVC: UIViewController {

    let months = ["January" , "February" , "March" , "April" , "May" , "June" , "July" , "August"]
    let unitsSold = [10.0,20.0,30.0,20.0,20.0,10.0,15.0,20.0]
    let unitsSold1 = [20.0,30.0,50.0,40.0,30.0,20.0,45.0,50.0]

    var dataEntries: [BarChartDataEntry] = []
    @IBOutlet var barChartView: BarChartView!

    override func viewDidLoad() {
        super.viewDidLoad()

        setChartBarGroupDataSet(dataPoints: months, values: unitsSold, values2: unitsSold1, sortIndex: 0)
    }

    func setChartBarGroupDataSet(dataPoints: [String], values: [Double], values2: [Double],sortIndex:Int) {
        for i in 0..<dataPoints.count
        {
            let dataEntry = BarChartDataEntry(x: values[i], y: Double(i))
            let dataEntry1 = BarChartDataEntry(x: values2[i], y: Double(i))
            dataEntries.append(dataEntry)
            dataEntries.append(dataEntry1)
        }

        let chartDataSet = BarChartDataSet(values: dataEntries, label: " ")

        var COLOR_SET = [UIColor]()
        COLOR_SET = [UIColor.red,UIColor.green]

        chartDataSet.setColors(COLOR_SET, alpha: 1.0)

        let dataSets: [BarChartDataSet] = [chartDataSet]

        let data = BarChartData(dataSets: dataSets)
        barChartView.data = data // Fatal error is here

        barChartView.descriptionText = "Bar Chart"
        barChartView.rightAxis.drawGridLinesEnabled = false
        barChartView.rightAxis.drawAxisLineEnabled = false
        barChartView.rightAxis.drawLabelsEnabled = false
        barChartView.animate(xAxisDuration: 2.0, yAxisDuration: 2.0, easingOption: .easeInBounce)   
    }
}

I am getting a fatal error on the line that I marked in the code.

fatal error: unexpectedly found nil while unwrapping an Optional value

Thank you in advance to people who help me.

Answer 1

I was able to run your code with no errors. I believe the problem you are facing is with the IBOutlet.

Make sure the selected class in your storyboard is BarChartView and that your view in storyboard is connected to the IBOutlet in your ViewController