这是一个解决方案 - 为视图引入回调属性并将其注入您的 inalinable 修饰符。使用 Xcode 12.1 / iOS 14.1 准备

struct MapView: UIViewRepresentable {
    func makeUIView(context: Context) -> MKMapView {
        let view = MKMapView()
        view.delegate = context.coordinator
        return view
    }
    
    func updateUIView(_ uiView: MKMapView,context: Context) {
    }

    func makeCoordinator() -> MapViewCoordinator {
        MapViewCoordinator(self)
    }
    
    private var tapCallback: ((MKAnnotationView) -> ())?    // << this one !!
    
    @inlinable public func onAnnotationTapped(site: @escaping (MKAnnotationView) -> ()) -> some View {
        var newMapView = self
        newMapView.tapCallback = site            // << here !!
        return newMapView
    }
    
    public class MapViewCoordinator: NSObject,MKMapViewDelegate {
        var mapView: MapView
        
        init(_ control: MapView) {
            self.mapView = control
        }
        
        public func mapView(_ mkMap: MKMapView,didSelect view: MKAnnotationView) {
            self.mapView.tapCallback?(view)     // << call !!
        }
    }
}