How to transfer data from map annotation to fullscreencover popup - swiftui

Question

I'm trying to transfer data after user click MapAnnotation. Currently after user click MapAnnotation it add data to selectedCourse and prints it before going if let course = selectedCourse. But some some reason selectedCourse is empty inside .fullScreenCover if statement
import SwiftUI
import MapKit
struct CourseMapView: View {
#ObservedObject var viewModel: CourseSearchViewModel
#State var isShowSheet = false
#State var region = MKCoordinateRegion(center: CLLocationCoordinate2D(latitude: 60.480960,
longitude: 22.239808),
span: MKCoordinateSpan(latitudeDelta: 0.1,
longitudeDelta: 0.1))
#State var selectedCourse: Course? = nil
func setCurrentLocation() {
region = MKCoordinateRegion(center: viewModel.location?.coordinate ?? CLLocationCoordinate2D(latitude: 60.480960, longitude: 22.239808), span: MKCoordinateSpan(latitudeDelta: 0.1, longitudeDelta: 0.1))
}
var body: some View {
ZStack {
if viewModel.location != nil {
Map(coordinateRegion: $region, interactionModes: .all, showsUserLocation: true, userTrackingMode: nil, annotationItems: viewModel.courses) { course in
MapAnnotation(coordinate: .init(latitude: course.location.latitude, longitude: course.location.longitude)) {
Image(systemName: "person")
.frame(width: 44, height: 44)
.onTapGesture(count: 1, perform: {
print("PRINT: \(course.name)")
selectedCourse = course
if selectedCourse != nil {
isShowSheet.toggle()
}
print("\(selectedCourse)")
})
}
}
.ignoresSafeArea()
} else {
Text("locating user location")
}
}
.fullScreenCover(isPresented: $isShowSheet, content: {
if let course = selectedCourse {
LocationInfoView(viewModel: LocationInfoViewModel(course: course))
.environment(\.showingSheet, self.$isShowSheet)
}
})
.alert(item: $viewModel.alertItem, content: { alertItem in
Alert(title: alertItem.title, message: alertItem.message, dismissButton: alertItem.dismissButton)
})
.onAppear {
setCurrentLocation()
}
}
}

Answer 1

You should use an other signature of .fullScreenCover :
func fullScreenCover<Item, Content>(item: Binding<Item?>, onDismiss: (() -> Void)? = nil, #ViewBuilder content: #escaping (Item) -> Content)
In this way :
.fullScreenCover(item: $selectedCourse) { course in
// content
}
In your example, item: will be a Course?. When you pass a Course the fullScreenCover is presented ; nil and it's closed.
So you could use a #Binding in your LocationInfoView to dismiss the fullScreenCover. But it looks like you prefer to use an EnvironmentKey. You must therefore modify it:
private struct SelectedCourseKey: EnvironmentKey {
static let defaultValue: Binding<Course?> = .constant(nil)
}
extension EnvironmentValues {
var selectedCourse: Binding<Course?> {
get { self[SelectedCourseKey.self] }
set { self[SelectedCourseKey.self] = newValue }
}
}
In your LocationInfoView:
struct LocationInfoView: View {
#Environment(\.selectedCourse) var selectedCourse: Binding<Course?>
var viewModel: LocationInfoViewModel
var body: some View {
VStack {
Button("close") {
selectedCourse.wrappedValue = nil
}
// some code
}
}
}
And finally, in your CourseMapView :
.fullScreenCover(item: $selectedCourse) { course in
if let course = course {
LocationInfoView(viewModel: LocationInfoViewModel(course: course))
.environment(\.selectedCourse, self.$selectedCourse)
}
}