GMSGeocoder entertain last request only

ReverseGeoCodingViewModel.swift

class ReverseGeoCodingViewModel {
    var requestIdentifier: Int = 0
    
    func reverseGeoCodeLocation(_ coordinate: CLLocationCoordinate2D,
                                completion: @escaping GMSReverseGeocodeCallback) {
        
        self.requestIdentifier += 1
        let currentRequestIdentifier = self.requestIdentifier
        
        let geocoder = GMSGeocoder()
        geocoder.reverseGeocodeCoordinate(coordinate) { response, error in
            
            guard currentRequestIdentifier >= self.requestIdentifier else {
                return
            }
            
            completion(response, error)
        }
    }
}