Efficiently Fetching Multiple Images from Firebase - swift

Question

My app will have lists of images like shown in the below example:
To fetch an individual image from firebase, I defined a ViewModel class with the single image as a UIImage property. The appropriate view can then update with published changes to this ViewModel. With several--and in fact an arbitrary amount--of images in a list, I don't imagine that giving each one its own ViewModel will be efficient, especially because I imagine that I'll have to ForEach to loop through each image reference and create a ViewModel inside the parent view. This seems problematic because whenever the parent view is recreated I'm doing an O(n) operation to create and initialize view models for each image, not to mention the time it takes to re-fetch.
Is there a way to fetch multiple images from inside one ViewModel, storing them as [UIImage]? I would presumbably give this ViewModel an array of references. Alternatively, what architecture would you suggest to efficiently fetch any number of images from firebase given an array (of unknown size) of storage references?
I can provide more detail / code as needed.
This seems to work...
class MultipleImageFetcher: ObservableObject {
var firebaseManager: FirebaseManager
var imageDictionary: [String: UIImage] = [:]
#Published var isReady = false
init(_ firebaseManager: FirebaseManager) {
self.firebaseManager = firebaseManager
}
func fetchAllImages(references: [String]) {
for refID in references {
fetchIndividualImage(id: refID, totalNum:
references.count)
}
}
func fetchIndividualImage(id: String, totalNum: Int) {
let ref = getRefURL(uid: id)
ref.getData(maxSize: 2051240) { data, error in
if let error = error {
print("Error: \(error)")
return
}
self.imageDictionary[id] = UIImage(data: data!)
self.checkIsReady(num: totalNum)
}
}
func getRefURL(uid: String) -> StorageReference {
return firebaseManager.STORAGE.reference().child(uid)
}
func checkIsReady(num: Int) {
if imageDictionary.count == num {
self.isReady = true
} else {
self.isReady = false
}
}
}
struct ImageView: View {
#ObservedObject var fetcher: MultipleImageFetcher
init(_ firebaseManager: FirebaseManager) {
self.fetcher = MultipleImageFetcher(firebaseManager)
}
var body: some View {
Button {
fetcher.fetchAllImages(references:
["KXKFM94sk5OTyld2VsCQdhijd6m1", "MtgRaKMwyQfYX2uxuHs3iH3pLB52"])
} label: {
Text("Load Image")
}
if fetcher.isReady {
Text("Is Ready")
} else {
Text("Loading...")
}
}
}