在CorePlot中触摸plotSymbol

import CorePlot

class ViewController: UIViewController, CPTPlotSpaceDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        let graph = CPTXYGraph(frame: CGRect(x: 0, y: 0, width: 320, height: 200))
        let hostingView = CPTGraphHostingView(frame: graph.bounds)
        hostingView.hostedGraph = graph
        view.addSubview(hostingView)

        let plotSpace = graph.defaultPlotSpace as! CPTXYPlotSpace
        plotSpace.delegate = self

        let plotSymbol = CPTScatterPlot(frame: CGRect.zero)
        plotSymbol.dataSource = self
        plotSymbol.plotSymbol = CPTPlotSymbol.ellipsePlotSymbol()
        plotSymbol.plotSymbolMarginForHitDetection = 5.0
        graph.addPlot(plotSymbol)
    }

    func plotSpace(_ plotSpace: CPTPlotSpace, shouldHandlePointingDeviceDownEvent event: UIEvent, atPoint point: CGPoint) -> Bool {
        if let plotSymbol = plotSpace.plotAreaFrame?.plotArea().plotGroups.first?.plots.first as? CPTScatterPlot {
            if plotSymbol.hitTest(point) {
                // Handle touch down event on plotSymbol
                return true
            }
        }
        return false
    }

    func plotSpace(_ plotSpace: CPTPlotSpace, shouldHandlePointingDeviceDraggedEvent event: UIEvent, atPoint point: CGPoint) -> Bool {
        if let plotSymbol = plotSpace.plotAreaFrame?.plotArea().plotGroups.first?.plots.first as? CPTScatterPlot {
            if plotSymbol.hitTest(point) {
                // Handle touch dragged event on plotSymbol
                return true
            }
        }
        return false
    }

    func plotSpace(_ plotSpace: CPTPlotSpace, shouldHandlePointingDeviceUpEvent event: UIEvent, atPoint point: CGPoint) -> Bool {
        if let plotSymbol = plotSpace.plotAreaFrame?.plotArea().plotGroups.first?.plots.first as? CPTScatterPlot {
            if plotSymbol.hitTest(point) {
                // Handle touch up event on plotSymbol
                return true
            }
        }
        return false
    }
}

extension ViewController: CPTScatterPlotDataSource {

    func numberOfRecords(for plot: CPTPlot) -> UInt {
        return 3
    }

    func number(for plot: CPTPlot, field: UInt, record: UInt) -> Any? {
        switch field {
        case 0:
            return record + 1
        case 1:
            return record * 2
        default:
            return nil
        }
    }
}