Problem with callout button and firestore in swift - swift

Question

I have 5 collections on Firestore. With the data of the documents of those collections, I create annotations of different types and display them on a map view.
The problem is that I want to pass all the information that is stored in each annotation and display it on another view controller, that appears when you press the callout button.
I can't figure out a way of referencing the annotation I'm pressing and then pass the data to the other screen.
This is my first time using databases and I don't have many experience, so I would appreciate some help.
Thanks!

Answer 1

It's difficult to give a specific answer since I don't know the full scope of your features. But this is how you generally do it.
First when you create the MKAnnotation subclass, you define a property to hold an object that you can reference later. For example, say I'm showing restaurants and supermarkets in a map.
class RestaurantAnnotation: NSObject, MKAnnotation {
let restaurant: Restaurant
var title: String? {
return restaurant.name
}
var coordinate: CLLocationCoordinate2D {
return restaurant.coordinate
}
init(restaurant: Restaurant) {
self.restaurant = restaurant
super.init()
}
}
struct Restaurant {
let name: String
let coordinate: CLLocationCoordinate2D
}
Same goes for the supermarkets.
Then when you create the annotation, you pass the Restaurant object to it.
let restaurant = Restaurant(name: "McDonald's", coordinate: CLLocationCoordinate2D(latitude: 27.2831, longitude: -127.831))
let restaurantAnnotation = RestaurantAnnotation(restaurant: restaurant)
mapView.addAnnotation(restaurantAnnotation)
You implement the mapView(_:annotationView:calloutAccessoryControlTapped:) delegate method to be notified when the user taps on the callout button in annotations. In it, you can easily reference the object you passed to it earlier.
func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
if let annotation = view.annotation as? RestaurantAnnotation {
print(annotation.restaurant)
} else if let annotation = view.annotation as? SupermarketAnnotation {
print(annotation.supermarket)
}
}
And you can use that data to do whatever you want after that. In your case, pass it to a new screen.