今天想要來介紹Swift 圖表的第三方套件，未來也有機會可以使用到作為資料的呈現

使用cocoapods來安裝

pod 'Charts'

在專案中要import套件

import Charts

使用Xib建立該View，這些View都是繼承自UIView
記得要使用某種特定類型的Charts要先看看文件，你要使用哪種charts，customClass使用該Class

舉個例子我要使用折線圖，我的customClass就要使用lineChartView

開始建構我的線條圖

class LineChartViewController: UIViewController {

    @IBOutlet weak var lineChartView: LineChartView!

    // 我的線圖的每筆資料
    let item2 = [
        BarChartDataEntry(x: 14, y: 8),
        BarChartDataEntry(x: 15, y: 19),
        BarChartDataEntry(x: 16, y: 12),
        BarChartDataEntry(x: 17, y: 22)
    ]

    override func viewDidLoad() {
        super.viewDidLoad()
        let lineChartDataSet2 = LineChartDataSet(entries: item2, label: "油價")
        // 是否開啟圓圈
        lineChartDataSet2.drawCirclesEnabled = false
        // 設定線條間的樣式
        lineChartDataSet2.mode = .cubicBezier
        // 設定顏色
        lineChartDataSet2.colors = [.green]
        // 是否開啟十字highlight線
        lineChartDataSet2.highlightEnabled = false

        // 填滿下方
        lineChartDataSet2.drawFilledEnabled = true
        let gradientColors = [UIColor.green.cgColor, UIColor.clear.cgColor] // Colors of the gradient
        let colorLocations:[CGFloat] = [1.0, 0.0] // Positioning of the gradient
        let gradient = CGGradient(colorsSpace: CGColorSpaceCreateDeviceRGB(), colors: gradientColors as CFArray, locations: colorLocations) // Gradient Object
        let gradienFill = LinearGradientFill(gradient: gradient!, angle: 120.0) // Set the Gradient
        let colorFill = ColorFill.init(cgColor: UIColor.green.cgColor)
        // 開啟漸層
        lineChartDataSet2.fill = gradienFill

        let lineDatasets = [lineChartDataSet2]
        let lineChartData = LineChartData(dataSets: lineDatasets)
        // 客製化下方的型別
        let formatter = NumberFormatter()
        formatter.positiveSuffix = "年"
        lineChartView.xAxis.valueFormatter = DefaultAxisValueFormatter(formatter: formatter)
        // Xaxis的位置
        lineChartView.xAxis.labelPosition = .bottom
        // Xaxis後方的Grid間隔
        lineChartView.xAxis.granularityEnabled = true
        lineChartView.xAxis.granularity = 1.0

        // 餵進去Data
        lineChartView.data = lineChartData

        // Do any additional setup after loading the view.
    }
}

成果展示