如何聚焦 Google 使用 swiftUI 视图在启动时将相机映射到用户的当前位置

Question

我正在尝试制作一个使用 Google 地图并在应用打开时关注用户位置的应用。

现在我正在初始化地图，在按下 Google 地图固有的 'myLocation' 按钮后我无法聚焦在用户位置上，但是地图的相机一直聚焦到指定的位置位置而不是用户位置。

我使用这 2 个教程到达了现在的位置： - https://developers.google.com/maps/documentation/ios-sdk/start - https://www.raywenderlich.com/197-google-maps-ios-sdk-tutorial-getting-started

在搜索 Google 和此处之后，似乎我需要利用 CLLocationManager() 来获取用户的设备坐标，然后以某种方式使用它？我认为我关于 CLLocationManager() 的代码可能放在错误的文件中或使用不当，但我没有收到任何错误。

我的代码是这样工作的：SceneDelegate.swift 将我的 LandmarkList.swift 设置为 rootViewController。然后 LandmarkList 调用 GoogMapView.swift 来显示 Google 地图的实例。

SceneDelegate.swift:

我想我在这里对locationManager的使用可能是错误的？

import UIKit
import SwiftUI
import GoogleMaps
import GooglePlaces
import CoreLocation



class SceneDelegate: UIResponder, UIWindowSceneDelegate, CLLocationManagerDelegate {


    var window: UIWindow?
    private let locationManager = CLLocationManager()


    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
        // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
        // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).

        // Use a UIHostingController as window root view controller
        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = UIHostingController(rootView: LandmarkList())
            self.window = window
            window.makeKeyAndVisible()
        }

        locationManager.requestAlwaysAuthorization()

        if CLLocationManager.locationServicesEnabled() {
            locationManager.delegate = self
            locationManager.desiredAccuracy = kCLLocationAccuracyBest
            locationManager.requestWhenInUseAuthorization()
        }

    }
}

LandmarkList.swift:

import SwiftUI

struct LandmarkList: View {

    @State private var searchText = ""
    @State private var locationText = ""


    var body: some View {


            ZStack(alignment: Alignment.top) {
                GoogMapView()
                    .frame(height: 750)


                SlideOverCard {
                    VStack(alignment: .leading) {
                        List(landmarkData) { landmark in
                            NavigationLink(destination: LandmarkDetail(landmark: landmark)) {
                                LandmarkRow(landmark: landmark)
                            }
                        }

                    }
                        .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: .infinity, alignment: Alignment.topLeading)
                    }
        }
    }
}

GoogMapView.swift:

注意：下面的打印语句只有returns'用户位置未知'

import SwiftUI
import UIKit
import GoogleMaps
import GooglePlaces
import CoreLocation


struct GoogMapView : UIViewRepresentable {

        let marker : GMSMarker = GMSMarker()

        //Creates a `UIView` instance to be presented.
        func makeUIView(context: Context) -> GMSMapView {
            // Create a GMSCameraPosition
            let camera = GMSCameraPosition.camera(withLatitude: 42.361145, longitude: -71.057083, zoom: 16.0)
            let mapView = GMSMapView.map(withFrame: CGRect.zero, camera: camera)
            mapView.setMinZoom(14, maxZoom: 20)
            mapView.settings.compassButton = true
            mapView.isMyLocationEnabled = true
            mapView.settings.myLocationButton = true
            mapView.settings.scrollGestures = true
            mapView.settings.zoomGestures = true
            mapView.settings.rotateGestures = true
            mapView.settings.tiltGestures = true
            mapView.isIndoorEnabled = false

            if let mylocation = mapView.myLocation {
              print("User's location: \(mylocation)")
            } else {
              print("User's location is unknown")
            }

            return mapView
        }

//        Updates the presented `UIView` (and coordinator) to the latestconfiguration.
    func updateUIView(_ mapView: GMSMapView, context: Context) {
        // Creates a marker in the center of the map.
        marker.position = CLLocationCoordinate2D(latitude: 42.361145, longitude: -71.057083)
        marker.title = "Boston"
        marker.snippet = "USA"
        marker.map = mapView
    }
}

同样，我认为我在 SceneDelegate.swift 中关于 locationManager 的代码会使 GoogleMaps 相机的实例在启动时聚焦于用户位置，但它不会。

有人知道我做错了什么吗？

Answer 1

您可以通过 "pretending" 您的视图是 ViewController 来实现。尝试将 GoogleMapView 设置为代表。然后把你的初始化代码放在makeUIView然后遵守协议：

struct GoogMapView : CLLocationManagerDelegate {

private let locationManager = CLLocationManager()

  func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {

    guard status == .authorizedWhenInUse else {
      return
    }

    locationManager.startUpdatingLocation()


    mapView.isMyLocationEnabled = true
    mapView.settings.myLocationButton = true
  }


  func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    guard let location = locations.first else {
      return
    }


    mapView.camera = GMSCameraPosition(target: location.coordinate, zoom: 15, bearing: 0, viewingAngle: 0)


    locationManager.stopUpdatingLocation()
  }
}

以上摘自https://www.raywenderlich.com/197-google-maps-ios-sdk-tutorial-getting-started。

Answer 2

使用此处和 Whosebug 上的其他评论，我制定了这个解决方案：

//
//  GoogMapView.swift
//  Landmarks
//
//  Created by Zahr Lyttle on 10/14/19.
//  Copyright © 2019 Apple. All rights reserved.
//

import SwiftUI
import UIKit
import GoogleMaps
import GooglePlaces
import CoreLocation
import Foundation



struct GoogMapView: View {
    var body: some View {
        GoogMapControllerRepresentable()
    }
}


class GoogMapController: UIViewController, CLLocationManagerDelegate {
    var locationManager = CLLocationManager()
    var mapView: GMSMapView!
    let defaultLocation = CLLocation(latitude: 42.361145, longitude: -71.057083)
    var zoomLevel: Float = 15.0
    let marker : GMSMarker = GMSMarker()


    override func viewDidLoad() {
        super.viewDidLoad()

        locationManager = CLLocationManager()
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.requestAlwaysAuthorization()
        locationManager.distanceFilter = 50
        locationManager.startUpdatingLocation()
        locationManager.delegate = self

        let camera = GMSCameraPosition.camera(withLatitude: defaultLocation.coordinate.latitude, longitude: defaultLocation.coordinate.longitude, zoom: zoomLevel)
        mapView = GMSMapView.map(withFrame: view.bounds, camera: camera)
        mapView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        mapView.isMyLocationEnabled = true
        mapView.setMinZoom(14, maxZoom: 20)
        mapView.settings.compassButton = true
        mapView.isMyLocationEnabled = true
        mapView.settings.myLocationButton = true
        mapView.settings.scrollGestures = true
        mapView.settings.zoomGestures = true
        mapView.settings.rotateGestures = true
        mapView.settings.tiltGestures = true
        mapView.isIndoorEnabled = false

//        if let mylocation = mapView.myLocation {
//          print("User's location: \(mylocation)")
//        } else {
//          print("User's location is unknown")
//        }

        marker.position = CLLocationCoordinate2D(latitude: 42.361145, longitude: -71.057083)
        marker.title = "Boston"
        marker.snippet = "USA"
        marker.map = mapView

        // Add the map to the view, hide it until we&#39;ve got a location update.
        view.addSubview(mapView)
//        mapView.isHidden = true

    }

    // Handle incoming location events.
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
      let location: CLLocation = locations.last!
      print("Location: \(location)")

      let camera = GMSCameraPosition.camera(withLatitude: location.coordinate.latitude, longitude: location.coordinate.longitude, zoom: zoomLevel)

      if mapView.isHidden {
        mapView.isHidden = false
        mapView.camera = camera
      } else {
        mapView.animate(to: camera)
      }

    }

    // Handle authorization for the location manager.
    func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
      switch status {
      case .restricted:
        print("Location access was restricted.")
      case .denied:
        print("User denied access to location.")
        // Display the map using the default location.
        mapView.isHidden = false
      case .notDetermined:
        print("Location status not determined.")
      case .authorizedAlways: fallthrough
      case .authorizedWhenInUse:
        print("Location status is OK.")
      }
    }

    // Handle location manager errors.
    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) {
      locationManager.stopUpdatingLocation()
      print("Error: \(error)")
    }

}


struct GoogMapControllerRepresentable: UIViewControllerRepresentable {
    func makeUIViewController(context: UIViewControllerRepresentableContext<GMControllerRepresentable>) -> GMController {
        return GMController()
    }

    func updateUIViewController(_ uiViewController: GMController, context: UIViewControllerRepresentableContext<GMControllerRepresentable>) {

    }
}

Answer 3

我终于弄清楚了如何立即关注 "my location"，而不是要求用户输入。这里有更多详细信息...希望对您有所帮助！

updateUIView

您希望在检索到用户位置时调用 updateUIView。根据我的阅读，当 @State 或 @Binding 对象更改（或 @ObservedObject）时，将调用 updateUIView。因此，UIViewRepresentable 需要其中之一。对于下面的代码，我使用 @ObservedObject。每当 @ObservedObject 的 @Published 属性之一发生变化时，将调用 updateUIView。

创建观察对象

我创建了一个符合ObservableObject协议的class（LocationManager）。
在class中，我将lastKnownLocation暴露为@Published属性。如上所述，当 lastKnownLocation 更新时，LocationManager class 实例的任何订阅者都将看到这些更新

获取用户坐标

CLLocationManager 用于获取用户位置的更新。
我创建的LocationManagerclass实现了CLLocationManager
更新用户位置时调用委托函数didUpdateLocations。在该函数中，我然后更新 @Published 属性以便 UIViewRepresentable 看到这些更改，并且相应地自动调用 updateUIView。

UIViewRepresentable

import SwiftUI
import GoogleMaps
import Combine

struct HomeView: UIViewRepresentable {

    // Listen to changes on the locationManager
    @ObservedObject var locationManager = LocationManager()

    func makeUIView(context: Self.Context) -> GMSMapView {

        // Just default the camera to anywhere (this will be overwritten as soon as myLocation is grabbed
        let camera = GMSCameraPosition.camera(withLatitude: 0, longitude: 0, zoom: 16.0)
        let mapView = GMSMapView.map(withFrame: CGRect.zero, camera: camera)
        mapView.setMinZoom(14, maxZoom: 20)
        mapView.settings.compassButton = true
        mapView.isMyLocationEnabled = true
        mapView.settings.myLocationButton = true
        mapView.settings.scrollGestures = true
        mapView.settings.zoomGestures = true
        mapView.settings.rotateGestures = true
        mapView.settings.tiltGestures = true
        mapView.isIndoorEnabled = false

        return mapView
    }

    func updateUIView(_ mapView: GMSMapView, context: Self.Context) {

        // When the locationManager publishes updates, respond to them
        if let myLocation = locationManager.lastKnownLocation {
            mapView.animate(toLocation: myLocation.coordinate)
            print("User's location: \(myLocation)")
        }
    }
}

LocationManager class:

class LocationManager: NSObject, CLLocationManagerDelegate, ObservableObject {

    // Publish the user's location so subscribers can react to updates
    @Published var lastKnownLocation: CLLocation? = nil
    private let manager = CLLocationManager()

    override init() {
        super.init()
        self.manager.delegate = self
        self.manager.startUpdatingLocation()
    }

    func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
        if status == .authorizedWhenInUse {
            self.manager.startUpdatingLocation()
        }
    }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        // Notify listeners that the user has a new location
        self.lastKnownLocation = locations.last
    }
}

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