swift : How I can save array data in Cloud Storage?

Question

import Foundation
import Firebase
import FirebaseStorage
import FirebaseStorageSwift
import UIKit

class UploadViewModel : ObservableObject {
    
    @Published var loading : Bool = false
    
    func storeImageWithUrl(images : [UIImage], completion : @escaping (_ urls : [String]) -> ()) {
        
        self.loading = true
        
        var urls : [String] = []
        
        for image in images {
            
            let ref = Storage.storage().reference(withPath: UUID().uuidString)
            
            guard let imageData = image.jpegData(compressionQuality: 0.5) else {return}
            
            ref.putData(imageData, metadata: nil) { metaData, error in
                if let error = error {
                    print("failed to push image cause of error")
                    return
                }
                
                ref.downloadURL { url, error in
                    if let error = error {
                        print("error to make url")
                        return
                    }
                    guard let url = url else {return}
                    urls.append(url.absoluteString)
                    print(urls)
                }
            }
        }
        completion(urls)
    }
    
    func storeItemInformation(title : String, description : String, category : String, contactInfo : String, price : String, imageUrls : [String], timeStamp : Date = Date(), completion : @escaping (_ result : Bool) -> ()) {
        
        let uid = AuthService.instance.makeUid()
        
        guard let userData = ["title": title, "description" : description, "category" : category, "price" : price, "imageURL" : imageUrls, "timestamp" : timeStamp, "contactInfo" : contactInfo] as? [String : Any] else { return }
        
        Firestore.firestore()
            .collection("WholeItems")
            .document(UUID().uuidString)
            .setData(userData) { error in
                if let error = error {
                    print("Error to save whole Data")
                    completion(false)
                    return
                }
                print("Success to save whole data")
        
                Firestore.firestore()
                    .collection("UserItems")
                    .document(uid)
                    .collection(uid)
                    .document(UUID().uuidString)
                    .setData(userData) { error in
                        if let error = error {
                            print("Error to save userData")
                            completion(false)
                            return
                        }
                        
                    self.loading = false
                    print("Success to save user data")
                    completion(true)
                }
        }
    }
}

The code above is about saving data with image. To save multiple images, I made several URLs about image in Storage and made completion using URLs to save data in firestore.

However, except imageURL array, Every data in the dictionary is saved well. I don't know why weren't the imageURLs saved to firestore.