如何让用户将图钉添加到地图并在SwiftUI中获取坐标？
如何让用户将图钉添加到地图并在SwiftUI中获取坐标？
提问于 2019-12-05 02:26:08
我有一张以芝加哥为中心的地图。我希望用户能够在地图上放置大头针/注释，然后检索这些坐标。地图加载芝加哥很好，但是我不能让注释代码工作。
具体来说，我似乎找不到SwiftUI的答案。只有Swift和Storyboard。我觉得我有99%的代码，但代码片段并不在正确的位置。我包含了错误所在的屏幕截图。谢谢你的帮助。
import SwiftUI
import MapKit
struct EntireMapView: UIViewRepresentable {
func updateUIView(_ mapView: MKMapView, context: Context) {
mapView.delegate = context.coordinator
let longPressGesture = UILongPressGestureRecognizer(target: mapView, action: #selector(EntireMapViewCoordinator.addAnnotation(gesture:)))
mapView.addGestureRecognizer(longPressGesture)
let span = MKCoordinateSpan(latitudeDelta: 0.3, longitudeDelta: 0.3)
var chicagoCoordinate = CLLocationCoordinate2D()
chicagoCoordinate.latitude = 41.878113
chicagoCoordinate.longitude = -87.629799
let region = MKCoordinateRegion(center: chicagoCoordinate, span: span)
mapView.setRegion(region, animated: true)
}
func makeUIView(context: Context) -> MKMapView {
let mapView = MKMapView(frame: .zero)
mapView.delegate = context.coordinator
return mapView
}
func makeCoordinator() -> EntireMapViewCoordinator {
return EntireMapViewCoordinator(self)
}
class EntireMapViewCoordinator: NSObject, MKMapViewDelegate {
var entireMapViewController: EntireMapView
init(_ control: EntireMapView) {
self.entireMapViewController = control
}
func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
return (annotation as? MKAnnotationView)!
}
@objc func addAnnotation(gesture: UILongPressGestureRecognizer) {
if gesture.state == .ended {
let point = gesture.location(in: self.mapView) **<--- ERROR HERE**
let coordinate = mapView.convert(point, toCoordinateFrom: mapView)
var annotation = MKPointAnnotation()
annotation.coordinate = coordinate
self.mapView.addAnnotation(annotation) **<--- ERROR HERE**
}
}
}
}
struct EntireMapView_Previews: PreviewProvider {
static var previews: some View {
EntireMapView()
}
}
回答 3
Stack Overflow用户
发布于 2020-03-23 11:21:26
这是一个完整的答案代码。这主要归功于@yeezy，因为通过这一行获得观点：let mapView = gestureRecognizer.view as? MKMApView是问题中的主要错误。
struct EntireMapView: UIViewRepresentable {
func updateUIView(_ mapView: MKMapView, context: Context) {
let span = MKCoordinateSpan(latitudeDelta: 0.3, longitudeDelta: 0.3)
var chicagoCoordinate = CLLocationCoordinate2D()
chicagoCoordinate.latitude = 41.878113
chicagoCoordinate.longitude = -87.629799
let region = MKCoordinateRegion(center: chicagoCoordinate, span: span)
mapView.setRegion(region, animated: true)
}
func makeUIView(context: Context) -> MKMapView {
let myMap = MKMapView(frame: .zero)
let longPress = UILongPressGestureRecognizer(target: context.coordinator, action: #selector(EntireMapViewCoordinator.addAnnotation(gesture:)))
longPress.minimumPressDuration = 1
myMap.addGestureRecognizer(longPress)
myMap.delegate = context.coordinator
return myMap
}
func makeCoordinator() -> EntireMapViewCoordinator {
return EntireMapViewCoordinator(self)
}
class EntireMapViewCoordinator: NSObject, MKMapViewDelegate {
var entireMapViewController: EntireMapView
init(_ control: EntireMapView) {
self.entireMapViewController = control
}
@objc func addAnnotation(gesture: UIGestureRecognizer) {
if gesture.state == .ended {
if let mapView = gesture.view as? MKMapView {
let point = gesture.location(in: mapView)
let coordinate = mapView.convert(point, toCoordinateFrom: mapView)
let annotation = MKPointAnnotation()
annotation.coordinate = coordinate
mapView.addAnnotation(annotation)
}
}
}
}
}Stack Overflow用户
发布于 2020-03-05 20:45:21
我不知道你是否还在寻找答案。但这里有一个。我在这个问题上挣扎了很久，我不知道我的答案是否正确，但它对我来说是有效的，所以这里是：
@objc func addAnnotation(gesture: UITapGestureRecognizer){
if let mapView = gestureRecognizer.view as? MKMApView{
let point = gestureRecognizer.location(in: mapView)
let coordinate = mapView.convert(point, toCoordinateFrom: mapView)
let annotation = MKPointAnnotation()
annotation.coordinate = coordinate
DispatchQueue.main.async{
mapView.addAnnotation(annotation)
}
}
}如您所见，我使用的不是UILongPressGestureRecognizer，而是UITapGestureRecognize，我采纳了您使用gestureRecognizers视图的想法。
免责声明:我不知道这是不是最好的方法！我半年前才开始进行swift/swiftUI编程:)，这是我的第一个答案。
对于进一步的实现:您应该只收集数组中的所有注释，并从updateUIView方法中更新mapView。我不知道我在这里使用DispatchQueue.main.async时是否正确。但是每当我遇到Ui的变化时，我认为你应该在主线程上做它
Stack Overflow用户
发布于 2019-12-27 15:03:59
我会从从updateUIView中移除mapView.delegate = context.coordinator开始。这应该只做一次，在makeUIView中(您已经在做了)。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/59182557
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