didSelect 上的 MapKit/MKMapViewDelegate：如果启用了用户位置，则底部工作表不会打开
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【中文标题】didSelect 上的 MapKit/MKMapViewDelegate：如果启用了用户位置，则底部工作表不会打开【英文标题】：MapKit/MKMapViewDelegate on didSelect: bottom sheet doesn't open if user location is enabled 【发布时间】：2020-07-27 15:56:51 【问题描述】：我正在尝试在 ios 上重建 Apple Maps 的注释选择行为。如果我点击地图图钉，它应该会打开一个底部表格，其中包含有关该地点的更多信息。
虽然已经对所有基本组件进行了编码，但如果在地图上启用了用户位置，我的底部工作表不会打开。
User Location disabled: bottom sheet opens correctly
User Location enabled: bottom sheet doesn’t open, but WHY?
如果启用了用户位置，为什么我的底部工作表打不开？我真的很感激一些意见。谢谢！
如何复制它：
-
根据您要测试的内容更改
MapMainView.swift 中的变量showCurrentLocation。
请不要忘记添加 Info.plist 条目 Privacy - Location When In Use Usage Description 和 Privacy - Location Always Usage Description 以访问您设备的本地位置。
ContentView.swift
import SwiftUI
struct ContentView: View
var body: some View
MapMainView()
MapMainView.swift
import Foundation
import SwiftUI
import MapKit
struct MapMainView: View
let showCurrentLocation = false
let locationFetcher = LocationFetcher()
@State var selectedPin: MapPin? = nil
@State var isBottomSheetOpen: Bool = false
@State var examplePins = [MapPin]()
var body: some View
GeometryReader geometry in
ZStack()
VStack()
Spacer()
BottomSheetView(isOpen: self.$isBottomSheetOpen, maxHeight: geometry.size.height * 0.3)
Text(String(self.selectedPin?.title ?? "no title")).foregroundColor(Color.black)
.edgesIgnoringSafeArea(.all)
.zIndex(1)
MapView(locationFetcher: self.locationFetcher, showCurrentLocation: self.showCurrentLocation, displayedPins: self.$examplePins, selectedPin: self.$selectedPin, isBottomSheetOpen: self.$isBottomSheetOpen)
.edgesIgnoringSafeArea(.all)
.onAppear
var currentLat: Double
var currentLng: Double
if self.showCurrentLocation
currentLat = self.locationFetcher.getCurrentCoordinates()?.latitude ?? 46.9457590197085
currentLng = self.locationFetcher.getCurrentCoordinates()?.longitude ?? 8.007923669708498
else
currentLat = 46.9457590197085
currentLng = 8.007923669708498
self.examplePins.append(MapPin(coordinate: CLLocationCoordinate2D(latitude: currentLat - 0.004, longitude: currentLng - 0.002), title: "First Pin"))
self.examplePins.append(MapPin(coordinate: CLLocationCoordinate2D(latitude: currentLat + 0.002, longitude: currentLng + 0.002), title: "Second Pin"))
self.examplePins.append(MapPin(coordinate: CLLocationCoordinate2D(latitude: currentLat - 0.002, longitude: currentLng + 0.004), title: "Third Pin"))
class MapPin: NSObject, MKAnnotation
let coordinate: CLLocationCoordinate2D
let title: String?
init(coordinate: CLLocationCoordinate2D, title: String? = nil)
self.coordinate = coordinate
self.title = title
MapView.swift
import SwiftUI
import MapKit
struct MapView: UIViewRepresentable
let locationFetcher: LocationFetcher
let showCurrentLocation: Bool
@Binding var displayedPins: [MapPin]
@Binding var selectedPin: MapPin?
@Binding var isBottomSheetOpen: Bool
func makeCoordinator() -> Coordinator
Coordinator(self)
func makeUIView(context: Context) -> MKMapView
let mapView = MKMapView()
mapView.delegate = context.coordinator
if showCurrentLocation
mapView.showsUserLocation = true
self.locationFetcher.attemptLocationAccess()
centerLocation(mapView: mapView, locationCoordinate: locationFetcher.getCurrentCoordinates())
else
centerLocation(mapView: mapView, locationCoordinate: CLLocationCoordinate2D(latitude: 46.9457590197085, longitude: 8.007923669708498))
return mapView
func updateUIView(_ mapView: MKMapView, context: Context)
if self.displayedPins.count != mapView.annotations.count
mapView.removeAnnotations(mapView.annotations)
mapView.addAnnotations(self.displayedPins)
func centerLocation(mapView: MKMapView, locationCoordinate: CLLocationCoordinate2D?)
if locationCoordinate != nil
let kilometerRadius = 1.5;
let scalingFactor = abs((cos(2 * Double.pi * locationCoordinate!.latitude / 360.0)));
let span = MKCoordinateSpan(latitudeDelta: kilometerRadius/111, longitudeDelta: kilometerRadius/(scalingFactor * 111))
let region = MKCoordinateRegion(center: locationCoordinate!, span: span)
mapView.setRegion(region, animated: true)
class Coordinator: NSObject, MKMapViewDelegate
var parent: MapView
init(_ parent: MapView)
self.parent = parent
func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView)
guard let pin = view.annotation as? MapPin else
return
mapView.setCenter(pin.coordinate, animated: true)
DispatchQueue.main.async
self.parent.selectedPin = pin
self.parent.isBottomSheetOpen = true
func mapView(_ mapView: MKMapView, didDeselect view: MKAnnotationView)
guard (view.annotation as? MapPin) != nil else
return
DispatchQueue.main.async
self.parent.selectedPin = nil
self.parent.isBottomSheetOpen = false
BottomSheetView.swift
import Foundation
import SwiftUI
struct BottomSheetView<Content: View>: View
@Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
@Binding var isOpen: Bool
let maxHeight: CGFloat
let minHeight: CGFloat
let content: Content
@GestureState private var translation: CGFloat = 0
private var offset: CGFloat
isOpen ? 0 : maxHeight - minHeight
private var indicator: some View
RoundedRectangle(cornerRadius: Constants.RADIUS)
.fill(Color.black)
.frame(
width: Constants.INDICATOR_WIDTH,
height: Constants.INDICATOR_HEIGHT
).onTapGesture
self.isOpen.toggle()
init(isOpen: Binding<Bool>, maxHeight: CGFloat, @ViewBuilder content: () -> Content)
self.minHeight = maxHeight * Constants.MIN_HEIGHT_RATIO
self.maxHeight = maxHeight
self.content = content()
self._isOpen = isOpen
var body: some View
GeometryReader geometry in
VStack(spacing: 0)
self.indicator.padding()
self.content
.frame(width: geometry.size.width, height: self.maxHeight, alignment: .top)
.background(Color.white)
.cornerRadius(Constants.RADIUS)
.frame(height: geometry.size.height, alignment: .bottom)
.offset(y: max(self.offset + self.translation, 0))
.animation(.interactiveSpring())
.gesture(
DragGesture().updating(self.$translation) value, state, _ in
state = value.translation.height
.onEnded value in
let snapDistance = self.maxHeight * Constants.SNAP_RATIO
guard abs(value.translation.height) > snapDistance else
return
self.isOpen = value.translation.height < 0
)
enum Constants
static let RADIUS: CGFloat = 16
static let INDICATOR_HEIGHT: CGFloat = 6
static let INDICATOR_WIDTH: CGFloat = 60
static let SNAP_RATIO: CGFloat = 0.25
static let MIN_HEIGHT_RATIO: CGFloat = 0
LocationFetcher.swift
import CoreLocation
import SwiftUI
class LocationFetcher: NSObject, CLLocationManagerDelegate
let locationManager = CLLocationManager()
override init()
super.init()
locationManager.delegate = self
func attemptLocationAccess()
guard CLLocationManager.locationServicesEnabled() else
return
locationManager.desiredAccuracy = kCLLocationAccuracyHundredMeters
if CLLocationManager.authorizationStatus() == .notDetermined
locationManager.requestWhenInUseAuthorization()
else
locationManager.requestLocation()
locationManager.startUpdatingLocation()
func getCurrentCoordinates() -> CLLocationCoordinate2D?
return locationManager.location?.coordinate
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])
func locationManager(_ manager: CLLocationManager, didFailWithError error: Error)
fatalError("error: \(error.localizedDescription)")
或者你可以在这里下载所有文件https://gofile.io/d/LSfli5
【问题讨论】：
【参考方案1】：我自己发现了问题。不仅是我的 MapPins，而且蓝色的位置圈也算作 mapView 注释。因此，如果启用了定位服务，我的 updateUIView() 会删除并在每个 didSelect 上添加我的所有注释，因为 self.displayedPins.count != mapView.annotations.count 始终为 false，这会导致底部表格突然消失。
在过滤注释后它终于起作用了：
func updateUIView(_ mapView: MKMapView, context: Context)
let displayedMapPins = mapView.annotations.filter annotation in
return annotation is MapPin
if self.mapPinsToDisplay.count != displayedMapPins.count
mapView.removeAnnotations(displayedMapPins)
mapView.addAnnotations(self.mapPinsToDisplay)
【讨论】：
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