swift - 如何使用 danielgindi/Charts 库和 Swift 3.0 绘制条形图

Question

问题陈述:由于在 swift 3.0 语法错误中使用“danielgindi/Charts 库”实现条形图时出现一些错误，因此无法运行。

Swift 3.0 中的实际错误:

纠正上述错误后，下一行又出现另一个错误，如下所示。

编码内容:

import Charts

class ChartViewController: UIViewController {

    @IBOutlet var barChartView: BarChartView!

    var months: [String]!
    var dataEntries: [BarChartDataEntry] = []


    override func viewDidLoad() {
        super.viewDidLoad()

        months = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]
        let unitsSold = [20.0, 4.0, 6.0, 3.0, 12.0, 16.0, 4.0, 18.0, 2.0, 4.0, 5.0, 4.0]
        setChart(dataPoints: months, values: unitsSold)

    }

    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: "Units Sold")

        let chartData = BarChartData(xVals: months, dataSet: chartDataSet)

        barChartView.data = chartData
    }

请帮助我，如何解决 swift 3.0 中的此类错误

Answer 1

我也遇到过这个问题。这是这里的这一行:

let dataEntry = BarChartDataEntry(x: Double(i), yValues: [values[i]])

您无法将 dataPoints: [String] 转换为 Double 类型。

我的解决方案是删除 Double。那么这不满足我的数据类型，所以我将它们全部设为 [Int] 类型，如下所示:

func setChart(dataPoints: [Int], values: [Int]) {

    self.noDataText = "You need to provide data for the chart."

    var dataEntries: [BarChartDataEntry] = []

    for i in 0..<dataPoints.count {
        let dataEntry = BarChartDataEntry(x: Double(i), y: Double(values[i]) )
        dataEntries.append(dataEntry)


    }

    let chartDataSet = BarChartDataSet(values: dataEntries, label: "Units Sold")
    let chartData = BarChartData(dataSet: chartDataSet)
    self.data = chartData

您可以将 [Int] 转换为 Double，这样就解决了我的问题。我将变量 Months: [String] 更改为

let months = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]