Grouping two or more annotations to a single annotation which are nearer while zooming out

Question

I am using iOS SDK of Mappls which uses MapplsMapView class to point out the annotations. I need to design the mapView in a way if it is zoomed out, the nearer or overlapping annotations should be updated to a single annotation. At the same time while zooming in, the grouped annotation should ungroup to individual annotations.

In MapKit of Apple, I can usually do this by checking whether the annotation is of type MKClusterAnnotation and update the image of the annotation like this :

func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
        if annotation.isKind(of: MKUserLocation.self) {
            return nil
        }
        
        if let annotation = annotation as? MKClusterAnnotation {
            if let selected = mapView.selectedAnnotations.first {
                let underCluster = annotation.memberAnnotations.contains { $0 === selected }
                if underCluster {
                    mapView.deselectAnnotation(selected, animated: false)
                }
            }
            let view = mapView.dequeueReusableAnnotationView(withIdentifier: "multipleRecords", for: annotation)
            let hidden = annotation.count > 99 ? "+99" : "\(annotation.count)"
            view.image = theme.clusterAnnotation.withOverlay(text: hidden)
            return view
        }
        return nil
    }

In Mappls, I implemented the same function like this:

func mapView(_ mapView: MGLMapView, viewFor annotation: MGLAnnotation) -> MGLAnnotationView? {
        if let cluster = annotation as? MGLCluster {
            print("Cluster found with count \(cluster.clusterPointCount)")
        }
        return nil
    }

But the above check is not itself passed. Am I missing something here? Please help out on this.