使用Google Maps SDK for iOS开发Swift应用：如何获取骑行与公交信息？

嘿，我来帮你搞定这个问题！你已经成功开启了交通图层，接下来要实现骑行和公交信息的展示与获取，Google Maps SDK其实提供了很直接的方案，分两部分给你拆解：

1. 快速显示骑行图层 #

Google Maps SDK内置了专门的骑行图层，可以一键开启，直接在地图上展示自行车道、骑行专用路线等基础设施：

import GoogleMaps

// 在你的地图视图控制器中添加这段代码
let bikeLayer = GMSBicyclingLayer()
bikeLayer.map = mapView // mapView是你的GMSMapView实例对象

2. 获取骑行路线规划 #

如果需要生成从起点到终点的具体骑行路线，就得用到Google Directions API（SDK的图层仅展示静态骑行设施，路线规划需要调用API）。注意要先在Google Cloud项目中启用Directions API，并准备好有效的API密钥。

示例代码（用URLSession发起请求并解析路线）：

func fetchBikeRoute(from origin: CLLocationCoordinate2D, to destination: CLLocationCoordinate2D) {
    let apiKey = "*你的Google API密钥*"
    let originStr = "\(origin.latitude),\(origin.longitude)"
    let destinationStr = "\(destination.latitude),\(destination.longitude)"
    
    guard let requestUrl = URL(string: "https://maps.googleapis.com/maps/api/directions/json?origin=\(originStr)&destination=\(destinationStr)&mode=bicycling&key=\(apiKey)") else {
        print("无效的请求URL")
        return
    }
    
    URLSession.shared.dataTask(with: requestUrl) { data, _, error in
        guard let data = data, error == nil else {
            print("请求失败：\(error?.localizedDescription ?? "未知错误")")
            return
        }
        
        do {
            // 解析返回的JSON数据，提取路线信息
            if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
               let routes = json["routes"] as? [[String: Any]],
               let firstRoute = routes.first,
               let polylineDict = firstRoute["overview_polyline"] as? [String: Any],
               let polylineStr = polylineDict["points"] as? String {
                
                // 将路线绘制到地图上
                let routePath = GMSPath(fromEncodedPath: polylineStr)
                let routePolyline = GMSPolyline(path: routePath)
                routePolyline.strokeColor = .systemBlue
                routePolyline.strokeWidth = 3.0
                routePolyline.map = self.mapView
                
                // 你还可以解析路线的距离、预计耗时等信息，按需展示给用户
            }
        } catch {
            print("JSON解析失败：\(error.localizedDescription)")
        }
    }.resume()
}

1. 显示公交图层 #

和骑行图层类似，SDK提供了公交专用图层，开启后会展示公交路线、站点、地铁线路等公共交通设施：

let transitLayer = GMSTransitLayer()
transitLayer.map = mapView

2. 获取公交路线规划与实时信息 #

公交路线规划

同样依赖Directions API，只需将请求参数mode设为transit即可获取换乘方案：

func fetchTransitRoute(from origin: CLLocationCoordinate2D, to destination: CLLocationCoordinate2D) {
    let apiKey = "*你的Google API密钥*"
    let originStr = "\(origin.latitude),\(origin.longitude)"
    let destinationStr = "\(destination.latitude),\(destination.longitude)"
    
    guard let requestUrl = URL(string: "https://maps.googleapis.com/maps/api/directions/json?origin=\(originStr)&destination=\(destinationStr)&mode=transit&key=\(apiKey)") else {
        print("无效的请求URL")
        return
    }
    
    URLSession.shared.dataTask(with: requestUrl) { data, _, error in
        guard let data = data, error == nil else {
            print("请求失败：\(error?.localizedDescription ?? "未知错误")")
            return
        }
        
        do {
            if let json = try JSONSerialization.jsonObject(with: data) as? [String: Any],
               let routes = json["routes"] as? [[String: Any]],
               let firstRoute = routes.first {
                
                // 解析公交换乘的详细步骤（比如步行到站点、乘坐的公交线路、换乘点等）
                if let legs = firstRoute["legs"] as? [[String: Any]], let firstLeg = legs.first {
                    if let steps = firstLeg["steps"] as? [[String: Any]] {
                        for step in steps {
                            if let transitDetails = step["transit_details"] as? [String: Any] {
                                let lineInfo = transitDetails["line"] as? [String: Any]
                                let lineName = lineInfo?["name"] as? String ?? "未知线路"
                                let headsign = transitDetails["headsign"] as? String ?? ""
                                print("乘坐 \(lineName) 路，方向：\(headsign)")
                            }
                        }
                    }
                }
                
                // 绘制公交路线到地图
                if let polylineDict = firstRoute["overview_polyline"] as? [String: Any],
                   let polylineStr = polylineDict["points"] as? String {
                    let routePath = GMSPath(fromEncodedPath: polylineStr)
                    let routePolyline = GMSPolyline(path: routePath)
                    routePolyline.strokeColor = .systemGreen
                    routePolyline.strokeWidth = 3.0
                    routePolyline.map = self.mapView
                }
            }
        } catch {
            print("JSON解析失败：\(error.localizedDescription)")
        }
    }.resume()
}

实时公交信息

如果需要获取公交实时到站时间等动态信息，需要启用Google Real-Time Transit API，调用方式类似，只需调整API请求的端点和参数，就能获取车辆位置、预计到站时间等数据。

• 所有API调用都需要有效的Google API密钥，并且要在Google Cloud Console中启用对应的API（Maps SDK for iOS、Directions API、Real-Time Transit API等）。
• 注意API的配额限制和计费规则，避免超出免费额度。
• 实际项目中推荐用Codable协议做类型安全的JSON解析，上面的示例用JSONSerialization是为了快速展示核心逻辑。

内容的提问来源于stack exchange，提问作者maral