method.swift

 func getCoordinates() {
        coordinates = []
        let queue = OperationQueue()
        let operation1 = BlockOperation {
            
            let geoCoder = CLGeocoder()
            for mapPoint in self.points {
                let dispatchGroup = DispatchGroup()
                dispatchGroup.enter()
                print("CurrentAlert.shared.locations.count: \(CurrentAlert.shared.locations.count)")
                if let location = CurrentAlert.shared.locations[mapPoint.address] {
                    self.coordinates.append(location)
                    dispatchGroup.leave()
                } else {
                    geoCoder.geocodeAddressString(mapPoint.address) { (placemarks, error) in
                        if let placemarks = placemarks, let location = placemarks.first?.location {
                            CurrentAlert.shared.locations[mapPoint.address] = CLLocationCoordinate2D(latitude: location.coordinate.latitude , longitude: location.coordinate.longitude)
                            self.coordinates.append(CLLocationCoordinate2D(latitude: location.coordinate.latitude , longitude: location.coordinate.longitude))
                        } else {
                            self.coordinates.append(nil)
                        }
                        dispatchGroup.leave()
                    }
                }
                dispatchGroup.wait()
            }
        }