SwiftUI中UIViewRepresentable封装的MKMapView添加点击手势无法获取坐标

坐标返回nil的核心原因是Coordinator中错误创建了独立的MapView实例：

• 你在Coordinator中定义的let parent = MapView()是全新的、未渲染的空实例，和实际在界面上加载的MapView没有关联，它的myMapView属性永远为nil
• 额外通过@State持有MKMapView实例的逻辑完全多余，手势识别器可以直接获取到触发事件的地图实例

struct MapView: UIViewRepresentable {
    typealias UIViewType = MKMapView

    class Coordinator: NSObject, MKMapViewDelegate {
        let sfCoord = CLLocationCoordinate2D(latitude: 37.7749, longitude: -122.4194)

        func mapView(_ mapView: MKMapView, didAdd views: [MKAnnotationView]) {
            if let annotationView = views.first, let annotation = annotationView.annotation, annotation is MKUserLocation {
                let region = MKCoordinateRegion(center: annotation.coordinate, latitudinalMeters: 2000, longitudinalMeters: 2000)
                mapView.setRegion(region, animated: true)
            }
        }
    
        @objc func addAnnotationOnTapGesture(sender: UITapGestureRecognizer) {
            guard sender.state == .ended, let mapView = sender.view as? MKMapView else { return }
            print("in addAnnotationOnTapGesture")
            let point = sender.location(in: mapView)
            print("point is \(point)")
            let coordinate = mapView.convert(point, toCoordinateFrom: mapView)
            print("coordinate.latitude is \(coordinate.latitude)")
            let annotation = MKPointAnnotation()
            annotation.coordinate = coordinate
            annotation.title = "Start"
            mapView.addAnnotation(annotation)
        }
    }

    func makeUIView(context: Context) -> MKMapView {
        let map = MKMapView()
        map.showsUserLocation = true
        map.delegate = context.coordinator
        let gRecognizer = UITapGestureRecognizer(target: context.coordinator, action: #selector(Coordinator.addAnnotationOnTapGesture(sender:)))
        map.addGestureRecognizer(gRecognizer)
        return map
    }

    func makeCoordinator() -> Coordinator {
        Coordinator()
    }

    func updateUIView(_ uiView: MKMapView, context: Context) {

    }
}

• 移除了多余的@State private var myMapView: MKMapView?属性和对应的异步赋值逻辑
• 删除了Coordinator中无意义的control属性和新建的parent实例
• 点击手势触发时直接通过sender.view获取当前点击的MKMapView实例，不需要额外持有引用
• 去掉了不必要的可选值绑定，获取到的mapView实例一定不为空，坐标转换不会再返回nil

内容的提问来源于stack exchange，提问作者JohnSF