Transferring Coordinates to a MapView with Pin - swiftui

Question

I am trying to display a map pin on a map. Upon entry of a transaction the details are saved along with the location coordinates. In a list of transaction entries, the user may click on an entry for more detail information including a small map showing the transaction location.
Based on Asperi's suggestions at adding a MapMarker to MapKit in swiftUI 2 it appears that I need to declare an identifiable structure in order to use a map pin.
In the DetailView the latitude and longitude are copied to a coordinate parameter before transmission to MapView.
struct DetailView: View {
var coordinate: CLLocationCoordinate2D {
CLLocationCoordinate2D(
latitude: item.entryLat,
longitude: item.entryLong)
}
var body: some View {
VStack {
MapView(coordinate: coordinate)
.ignoresSafeArea(edges: .all)
.frame(height: 400)
.padding(.vertical, 10)
}
}
}
MapView is where I'm having trouble. I'm not sure how to pass in my coordinates for the region and the marker (xxxxx). Copying` coordinate to the #State region and the marker produces the error "Argument passed to call that takes no arguments".
struct Marker: Identifiable {
let id = UUID()
var location: MapMarker
}
struct MapView: View {
var coordinate: CLLocationCoordinate2D
#State private var region = MKCoordinateRegion(center: CLLocationCoordinate2D(xxxxxxx), span: MKCoordinateSpan(latitudeDelta: 0.5, longitudeDelta: 0.5))
let markers = [Marker(location: MapMarker(coordinate: CLLocationCoordinate2D(xxxxxxx), tint: .red))]
var body: some View {
Map(coordinateRegion: $region, showsUserLocation: true,
annotationItems: markers) { marker in
marker.location
}.edgesIgnoringSafeArea(.all)
}
}

Answer 1

Sounds like for your application, declaring the region as a constant will work. The code would look like this:
struct Marker: Identifiable {
let id = UUID()
var location: MapMarker
}
struct MapView: View {
var coordinate: CLLocationCoordinate2D
var body: some View {
Map(coordinateRegion: .constant(MKCoordinateRegion(center: coordinate,
span: MKCoordinateSpan(latitudeDelta: 0.5, longitudeDelta: 0.5))),
showsUserLocation: true,
annotationItems: [Marker(location: MapMarker(coordinate: coordinate))]) { marker in
marker.location
}.edgesIgnoringSafeArea(.all)
}
}
If you still wanted to use it as a #State variable, you could use a custom init to set the value:
struct MapView: View {
var coordinate: CLLocationCoordinate2D
#State private var region : MKCoordinateRegion
init(coordinate : CLLocationCoordinate2D) {
self.coordinate = coordinate
_region = State(initialValue: MKCoordinateRegion(center: coordinate,
span: MKCoordinateSpan(latitudeDelta: 0.5, longitudeDelta: 0.5)))
}
var body: some View {
Map(coordinateRegion: $region,
showsUserLocation: true,
annotationItems: [Marker(location: MapMarker(coordinate: coordinate))]) { marker in
marker.location
}
.edgesIgnoringSafeArea(.all)
}
}
Lastly, I'm defining the markers array inline, but you could split it out into a computed property:
var markers : [Marker] {
[Marker(location: MapMarker(coordinate: coordinate))]
}
var body: some View {
Map(coordinateRegion: $region,
showsUserLocation: true,
annotationItems: markers) { marker in
marker.location
}
.edgesIgnoringSafeArea(.all)
}