如何从 geoJson 文件中提取值并将值传递给 iOS swift 中的表视图

Question

我正在尝试提取 geoJson 值并将其存储到数组中，并在 table 视图中列出值数组以在地图视图中显示路线。这里我用的是Mapbox for mapview，因为它支持室内导航。现在我可以直接从 geoJson 文件在地图视图中显示路线。但我需要将值提取到数组中，以便在 table 视图中列出值。

这是我尝试提取 geoJson 值的代码：

我为提取值创建的结构：

struct Collection : Decodable {
    let type : String
    let features : [Feature]
}

struct Feature : Decodable {
    let type : String
    let properties : Properties
    let geometry : Geometry
    // there is also geometry
}

struct Properties : Decodable {
    let name : String
}

struct Geometry : Decodable{
    let coordinates: [CLLocationCoordinate2D]
}

这是用于加载 geoJson 文件的代码：

 func loadGeoJson() {
    DispatchQueue.global().async {
        // Get the path for example.geojson in the app’s bundle  tbiMapbox.
        guard let jsonUrl = Bundle.main.url(forResource: "newData", withExtension: "geojson") else { return }
        guard let jsonData = try? Data(contentsOf: jsonUrl) else { return }
        DispatchQueue.main.async {
            self.drawPolyline(geoJson: jsonData)
            print("data::\(jsonData)")
        }
    }
}

此函数使用绘制折线作为坐标：

func drawPolyline(geoJson: Data) {
    guard let style = self.mapView.style else { return }

    let shapeFromGeoJSON = try! MGLShape(data: geoJson, encoding: String.Encoding.utf8.rawValue)
    let source = MGLShapeSource(identifier: "polyline", shape: shapeFromGeoJSON, options: nil)
    style.addSource(source)

    let layer = MGLLineStyleLayer(identifier: "polyline", source: source)

    layer.lineJoin = NSExpression(forConstantValue: "round")
    layer.lineCap = NSExpression(forConstantValue: "round")

    layer.lineColor = NSExpression(forConstantValue: UIColor(red: 59/255, green:178/255, blue:208/255, alpha:1))


    layer.lineWidth = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)",
                                   [14: 2, 18: 20])

    let casingLayer = MGLLineStyleLayer(identifier: "polyline-case", source: source)
    casingLayer.lineJoin = layer.lineJoin
    casingLayer.lineCap = layer.lineCap
    casingLayer.lineGapWidth = layer.lineWidth
    casingLayer.lineColor = NSExpression(forConstantValue: UIColor(red: 41/255, green:145/255, blue:171/255, alpha:1))
    casingLayer.lineWidth = NSExpression(format: "mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)",
                                         [14: 1, 18: 4])

    let dashedLayer = MGLLineStyleLayer(identifier: "polyline-dash", source: source)
    dashedLayer.lineJoin = layer.lineJoin
    dashedLayer.lineCap = layer.lineCap
    dashedLayer.lineColor = NSExpression(forConstantValue: UIColor.red)
    dashedLayer.lineOpacity = NSExpression(forConstantValue: 0.5)
    dashedLayer.lineWidth = layer.lineWidth
    dashedLayer.lineDashPattern = NSExpression(forConstantValue: [0, 1.5])

    style.addLayer(layer)
    style.addLayer(dashedLayer)
    style.insertLayer(casingLayer, below: layer)
}

对于table视图，现在我正在加载静态数据：

var nameArray = [String]()
var coordinatesArray = [CLLocationCoordinate2D]()

var nameARR = ["1", "2", "3"]

func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return nameARR.count
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! newTableViewCell

    cell.companyName.text = nameARR[indexPath.row]
    return cell
}

我使用的geoJson值：

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "properties": {},
      "geometry": {
        "type": "LineString",
        "coordinates": [
          [
            80.2226534485817,
            12.871137160770251
          ],
          [
            80.22263333201408,
            12.871145658917484
          ],
          [
            80.22264339029789,
            12.871184881131773
          ],
          [
            80.2225998044014,
            12.871194686684378
          ],
          [
            80.22260718047619,
            12.87121625889878
          ]
        ]
      }
    },
    {
      "type": "Feature",
      "properties": {
        "name": "Entrance - CZSM"
      },
      "geometry": {
        "type": "LineString",
        "coordinates": [
          [
            80.22256962954998,
            12.87123848481471
          ],
          [
            80.22255957126617,
            12.871204819088353
          ],
          [
            80.22259946912527,
            12.871195013536129
          ],
          [
            80.22264305502176,
            12.871184881131773
          ],
          [
            80.22263266146183,
            12.871145658917484
          ],
          [
            80.22265445441008,
            12.871135526511145
          ]
        ]
      }
    }
  ]
}

我的问题是 1.) 如何提取值 geoJson 文件？ 2.) 如何将提取的值传递给 table 视图？，当点击 table 视图单元格时，它会执行 segue 并传递相关的坐标索引。

Answer 1

您可以使用此结构来解析您发布的 JSON：

struct Geodata: Codable {
    let type: String
    let features: [Feature]
}

struct Feature: Codable {
    let type: String
    let properties: Properties
    let geometry: Geometry
}

struct Geometry: Codable {
    let type: String
    let coordinates: [[Double]]
}

struct Properties: Codable {
    let name: String?
}

并用

之类的东西解析它

guard let jsonUrl = Bundle.main.url(forResource: "newData", withExtension: "geojson") else { return }
guard let jsonData = try? Data(contentsOf: jsonUrl) else { return }
do {
   let geoData = try JSONDecoder().decode(Geodata.self, from: jsonData)
} catch { 
   print("\(error)") 
}

如何从 geoJson 文件中提取值并将值传递给 iOS swift 中的表视图

How to extract values from geoJson file and pass the value to tableview in iOS swift

json

geojson

ios

swift