How to populate loaded records from firebase? - swift

Question

I wrote the function to lad the records from firebase but there's an error
Escaping closure captures mutating 'self' parameter
The function is written as follows:
let db = Firestore.firestore()
#State var libraryImages: [LibraryImage] = []
mutating func loadImages() {
libraryImages = []
db.collection(K.FStore.CollectionImages.collectionName).getDocuments() { (querySnapshot, err) in
if let err = err {
print("Error getting documents: \(err)")
} else {
if let snapshotDocuments = querySnapshot?.documents {
for document in snapshotDocuments {
let documentData = document.data()
let title: String = documentData[K.FStore.CollectionImages.title] as! String
let thumbnailUrl: String = documentData[K.FStore.CollectionImages.thumbnailUrl] as! String
let svgUrl: String = documentData[K.FStore.CollectionImages.svgUrl] as! String
let libraryImageItem = LibraryImage(title: title, thumbnailUrl: thumbnailUrl, svgUrl: svgUrl)
self.libraryImages.append(libraryImageItem)
}
}
}
}
}
Does anyone know what is causing an error and how to get rid of it?

Answer 1

Move all this into reference type view model and use it as observed object in your view
Here is a demo of possible approach:
struct DemoView: View {
#ObservedObject var vm = ImagesViewModel()
// #StateObject var vm = ImagesViewModel() // << SwiftUI 2.0
var body: some View {
Text("Loaded images: \(vm.libraryImages.count)")
.onAppear {
self.vm.loadImages()
}
}
}
class ImagesViewModel: ObservableObject {
let db = Firestore.firestore()
#Published var libraryImages: [LibraryImage] = []
func loadImages() {
libraryImages = []
db.collection(K.FStore.CollectionImages.collectionName).getDocuments() { (querySnapshot, err) in
if let err = err {
print("Error getting documents: \(err)")
} else {
if let snapshotDocuments = querySnapshot?.documents {
var images = [LibraryImage]()
for document in snapshotDocuments {
let documentData = document.data()
let title: String = documentData[K.FStore.CollectionImages.title] as! String
let thumbnailUrl: String = documentData[K.FStore.CollectionImages.thumbnailUrl] as! String
let svgUrl: String = documentData[K.FStore.CollectionImages.svgUrl] as! String
let libraryImageItem = LibraryImage(title: title, thumbnailUrl: thumbnailUrl, svgUrl: svgUrl)
images.append(libraryImageItem)
}
DispatchQueue.main.async {
self.libraryImages = images
}
}
}
}
}
}