Map Annotation cluster

I need to display a photo for a group of annotations (cluster) on a map. The photo should be selected randomly from the annotations that are inside that cluster. Currently, my method only works if I assign a static variable for 'pinToDisplay' in the 'AllPins' class. However, this causes a memory leak when a lot of pins are added, since it stores the photo from Firebase data. If I remove the static property from the variable, memory usage becomes more efficient, but the cluster is unable to display a photo for a group of annotations. It still works for a single annotation though. here the code

class PinParsed: Codable {
    let createdDate, id, owner, updatedDate: String?
     let address: String?
     let approve: Bool?
     let category: [String]?
     let city: String?
     let country: String?
     let creator: String?
     let image: String?
     let img: String?
     let lat: String?
     let linkPinAll: String?
     let linkPinTitle, long: String?
     let subscrtag: [String]?
     let title: String?
     let gal: [GalClass]?
     let instagramLink, googleStreetViewURL: String?
}

class PinAnnotation : MKPointAnnotation {
    var pin: PinParsed!
    var image: String!
}

final class AllPins {

      static var pinToDisplay: [PinAnnotation]?
    deinit {
        print("allpins deinit")
    }

//This is in the class which is responsible for cluster

override var annotation: MKAnnotation? {
        didSet {
            guard let annotation = annotation as? MKClusterAnnotation else {
                return
            }
            countLabel.text = "\(annotation.memberAnnotations.count)"
        }
        
        
        willSet {
            guard let annotation = annotation as? MKClusterAnnotation else {
                return
            }
            var randomElement = annotation.memberAnnotations.randomElement()
            let latitude = randomElement?.coordinate.latitude
            let longitude = randomElement?.coordinate.longitude
            if latitude != nil, longitude != nil {
                if let allPins = AllPins.pinToDisplay {
                    allPins.forEach { pinAnnotation in
                        
                        if pinAnnotation.coordinate.latitude == latitude && pinAnnotation.coordinate.longitude == longitude {
                            if let url = URL(string: pinAnnotation.pin.img!) {
                                URLSession.shared.dataTask(with: url) { [weak self] (data, response, error) in
                                    if let error = error {
                                        print(error.localizedDescription, "cluster photo")
                                    }
                                    if let imageData = data  {
                                        DispatchQueue.main.async {
                                            self!.imageView.image = UIImage(data: imageData)
                                            self!.imageView.contentMode = .scaleAspectFill
                                        }
                                    }
                                }.resume()
                            }
                        }
                    }
                }
                
            }
        }