在swift 3.0中将坐标数组转换为geojson字符串

Posted 2023-02-16

【中文标题】在swift 3.0中将坐标数组转换为geojson字符串

【英文标题】：Convert coordinate array into a geojson string in swift 3.0

【发布时间】：2017-05-19 19:35:47

【问题描述】：

有没有一种方法可以轻松地将我的坐标数组转换为 geojson 字符串，以便我可以轻松地将其绘制在 mapbox-ios 地图中？

id: 1, lat: 37.54365964, lon: -122.36820328, date: 1483607009.98252
id: 2, lat: 37.63721702, lon: -122.43994642, date: 1483607387.95026
id: 3, lat: 37.64117709, lon: -122.44319877, date: 1483607403.98835
id: 4, lat: 37.64425086, lon: -122.44768593, date: 1483607419.95671
id: 5, lat: 37.64803999, lon: -122.45107063, date: 1483607435.98718
id: 6, lat: 37.65210789, lon: -122.45382878, date: 1483607451.98202
id: 7, lat: 37.65538199, lon: -122.45796869, date: 1483607467.99542
id: 8, lat: 37.65874435, lon: -122.46226986, date: 1483607483.98868
id: 9, lat: 37.66271988, lon: -122.46545406, date: 1483607500.00689
id: 10, lat: 37.66725462, lon: -122.46555909, date: 1483607515.00965
id: 11, lat: 37.67171694, lon: -122.46680447, date: 1483607530.01121
id: 12, lat: 37.67577633, lon: -122.46992933, date: 1483607545.96997
id: 13, lat: 37.68035365, lon: -122.47161149, date: 1483607563.00284
id: 14, lat: 37.68506394, lon: -122.47132223, date: 1483607579.00677
id: 15, lat: 37.68971271, lon: -122.47030274, date: 1483607595.01726
id: 16, lat: 37.69433345, lon: -122.47028874, date: 1483607611.01769
id: 17, lat: 37.69887099, lon: -122.4712903, date: 1483607627.04018
id: 18, lat: 37.70344977, lon: -122.47131242, date: 1483607642.97182
id: 19, lat: 37.7078706, lon: -122.46905887, date: 1483607659.93988
id: 20, lat: 37.71039615, lon: -122.46428839, date: 1483607675.97476

这是 mapbox-ios 中绘制的 geojson 的示例图像： mapbox-ios geojson line

这是我将纬度放入数组中的方法

            var coordinates = [Any]()

        for location in try db.prepare(locations) 
            print("id: \(location[id]), lat: \(location[lat]), lon: \(location[lon]), date: \(location[date])")

            var waypoints = [Any]()
            waypoints.append("\(location[lat])")
            waypoints.append("\(location[lon])")
            coordinates.append(waypoints)
        

这是我想要实现的示例代码格式。

    func convertLocationArrayToGeoJson(locations: [Any],_: ()) -> String 

    // convert the array of lat lon here to geojson string

    return "geojson string"

输出结果应该是这样的：

"type": "FeatureCollection",
"features": [
    "type": "Feature",
    "properties": 
        "name": "geojson-1"
    ,
    "geometry": 
        "type": "LineString",
        "coordinates": [
            [
                longitude1-value,
                latitude-value1
            ],
            [
                longitude2-value,
                latitude2-value
            ]

        ]
    
]

【问题讨论】：

你能展示你的自定义类结构吗？

@nirav-d，我已经用代码格式和预期结果更新了问题。你能帮忙吗？

我的意思是你需要向我们展示你是如何将这个 lat long 值存储在数组中的？

编辑你的问题，记住一件事永远不要在评论中添加代码，在你的问题中添加这个代码。

我已经在问题中添加了它。

【参考方案1】：

首先像这样更改您的coordinates 数组创建，并先附加long，然后附加lat，因为您希望JSON 采用该格式。

var coordinates = [Any]()
for location in try db.prepare(locations) 

    var waypoints = [Any]()
    waypoints.append("\(location[lon])")
    waypoints.append("\(location[lat])")
    coordinates.append(waypoints)

现在创建像这样的 POST json 字典。

let jsonDic: [String: Any] = [
                                 "type": "FeatureCollection",
                                 "features": [
                                      [
                                          "type": "Feature",
                                          "properties": ["name": "geojson-1"],
                                          "geometry": [
                                               "type": "LineString",
                                               "coordinates": coordinate
                                          ]
                                      ]
                                  ]
                              ]

现在如果想要JSON 数据或字符串，则可以使用JSONSerialization.data(withJSONObject:options:。

if let data = try? JSONSerialization.data(withJSONObject: jsonDic, options: .prettyPrinted) 
    //For JSON String
    let jsonStr = String(bytes: data, encoding: .utf8)

【讨论】：

@MarkAngeloHernandez 欢迎朋友 :)