如何使用mapbox-ios添加“大于符号”线条样式(示例:>>>>)

let layer = MGLLineStyleLayer(identifier: "line-style", source: source)
layer.lineJoin = NSExpression(forConstantValue: "round")
layer.lineCap = NSExpression(forConstantValue: "round")
layer.lineColor = NSExpression(forConstantValue: UIColor.red)
layer.lineWidth = NSExpression(forConstantValue: 2.0)
layer.lineDashPattern = NSExpression(forConstantValue: [0, 10, 10, 10]) // 设置线条样式为大于符号
mapView.style?.addLayer(layer)

let styleURL = URL(string: "mapbox://styles/mapbox/streets-v11") // 设置地图样式
mapView.styleURL = styleURL

let source = MGLVectorSource(identifier: "source-id", configurationURL: URL(string: "mapbox://mapbox.mapbox-streets-v8")) // 设置地图源
mapView.style?.addSource(source)

mapView.frame = view.bounds
mapView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
view.addSubview(mapView)

mapView.setCenter(CLLocationCoordinate2D(latitude: 37.7749, longitude: -122.4194), zoomLevel: 10, animated: false) // 设置地图中心点和缩放级别