Error for a function in the sorrounding Zstack, but the function has no errors

Question

I created the function getAnnotations and I get no errors when calling that function inside of my view, or even when I define the function, but the Map gets 2 error:

Initializer 'init(coordinateRegion:interactionModes:showsUserLocation:userTrackingMode:annotationItems:annotationContent:)' requires that 'MKPointAnnotation.Type.Element' conform to 'Identifiable'

and

Type 'MKPointAnnotation.Type' cannot conform to 'RandomAccessCollection'

Code for the function getAnnotations:

func getAnnotations(completion: @escaping (_ annotations: [MKPointAnnotation]?) -> Void) {
        let db = Firestore.firestore()
        
        db.collection("annotations").addSnapshotListener { (querySnapshot, err) in
            guard let snapshot = querySnapshot else {
                if let err = err {
                    print(err)
                }
                completion(nil) // return nil if error
                return
            }
            guard !snapshot.isEmpty else {
                completion([]) // return empty if no documents
                return
            }
            
            var annotations = [MKPointAnnotation]()
            
            for doc in snapshot.documents {
                if let lat = doc.get("lat") as? String,
                   let lon = doc.get("long") as? String,
                   let latitude =  Double(lat),
                   let longitude = Double(lon) {
                    let coord = CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
                    let annotation = MKPointAnnotation()
                    annotation.coordinate = coord
                    annotations.append(annotation)
                }
            }
            completion(annotations) // return array
        }
    }

And my view:

ZStack (alignment: .bottom) {
                Map(coordinateRegion: $viewModel.region, 
showsUserLocation: true, annotationItems: MKPointAnnotation) { annotations in
                    MapAnnotation(coordinate: annotations.coordinate) {
                        Circle()
                    }
                }
                .ignoresSafeArea()
                .tint(.pink)
                
                LocationButton(.currentLocation) {
                    viewModel.requestAllowOnceLocationPermission()
                }
                .foregroundColor(.white)
                .cornerRadius(8)
                .labelStyle(.iconOnly)
                .symbolVariant(.fill)
                .tint(.pink)
                .padding(.bottom)
                .padding(.trailing, 300)
            }
            .onAppear {
                getAnnotations({ (annotations) in
                    if let annotations = annotations {
                        print(annotations)
                    }
                })
            }

I tried to make this a synchronous function, but I'm still getting the 2 errors. Is it possible to resolve those first so I could see if my getAnnotations function actually works or no?

Answer 1

func getAnnotations(...) is asynchronous, because inside db.collection("annotations").addSnapshotListener... is asynchronous.

Use the func getAnnotations(completion: @escaping (_ annotations: [MKPointAnnotation]?) -> Void) {...} that you have now, and use this:

.onAppear {
    getAnnotations { annotations in
         annotations?.forEach { print("----> coordinate: \($0.coordinate)")  }
    }
}
             

Pay attention to the details, every bracket count, and they should be placed as shown.

Read the basics again at: https://docs.swift.org/swift-book/LanguageGuide/TheBasics.html

and do the tutorial at: https://developer.apple.com/tutorials/swiftui/