Missing argument for parameter "user" call - SwiftUi - ios

Question

I've been getting this error message in the "ProfileFeedView_Previews" and I could not figure out how to solve it. Help would be much appreciated.
Error Message: Missing argument for parameter "user" call
Here are my codes:
import SwiftUI
struct ProfileFeedView: View {
#ObservedObject var viewModel: ProfileViewModel
let columns: [GridItem] = [
GridItem(.flexible(), spacing: 0, alignment: nil),
GridItem(.flexible(), spacing: 0, alignment: nil)]
init(user: User) {
self.viewModel = ProfileViewModel(user: user)
}
var body: some View {
NavigationView {
ScrollView{
LazyVGrid(columns: columns, spacing: 5) {
ForEach(viewModel.folders) { folder in
FolderLineItem(folder: folder)
}
}
}.navigationTitle("Folders")
.navigationBarHidden(true)
.padding(.top, 50)
}
}
}
struct ProfileFeedView_Previews: PreviewProvider {
static var previews: some View {
ProfileFeedView()
class ProfileViewModel: ObservableObject {
#Published var folders = [Folder]()
private let service = FolderService()
let user: User
init(user: User) {
self.user = user
self.fetchUserFolders()
}
func fetchUserFolders() {
guard let uid = user.id else { return }
service.fetchUserFolders(forUID: uid) { folders in
self.folders = folders
for i in 0 ..< folders.count {
self.folders[i].user = self.user
}
}
}
}
struct FolderLineItem: View {
let folder: Folder
var body: some View {
VStack {
Image("Image 4")
.resizable()
.scaledToFill()
.frame(width: (UIScreen.main.bounds.width / 2) - 15, height: (UIScreen.main.bounds.width / 2) - 15)
.clipped()
.cornerRadius(8)
Text(folder.foldername)
.font(.callout)
.lineLimit(2)
.padding(.bottom, 15)
.padding(.trailing, 5)
}
}
}
struct FolderService {
func fetchUserFolders(forUID uid: String, completion: #escaping([Folder]) -> Void) {
Firestore.firestore().collection("folders")
.whereField("uid", isEqualTo: uid)
.getDocuments { snapshot, _ in
guard let documents = snapshot?.documents else { return }
let folders = documents.compactMap({ try? $0.data(as: Folder.self)})
completion(folders.sorted(by: { $0.timestamp.dateValue() > $1.timestamp.dateValue()}))
}
}
}
struct Folder: Identifiable, Decodable {
#DocumentID var id: String?
let foldername: String
let folderdescription: String
let timestamp: Timestamp
let uid: String
var user: User?
}
I am lost, and could not figured out what's causing the error. For context, I am a newbie and has only been coding for 2 months.

Answer 1

Your ProfileFeedView has an init function that receives a User:
init(user: User) {
self.viewModel = ProfileViewModel(user: user)
}
That means that you can't create an instance of that view without a user. But in your preview, that's what you try to do:
struct ProfileFeedView_Previews: PreviewProvider {
static var previews: some View {
ProfileFeedView()
}
}
(Added in closing braces, I assume that's a copy-and-paste error!)
You will need to have some way of creating a User object that your preview can access. How you do that can vary quite a lot, depending on where this information comes from in a "live" context.
But if User can be populated easily, one thing you can do is create an example static method that creates a user filled with dummy data:
extension User {
static var example: User {
User(name: "Jane Doe", ...) // etc
}
}
Then, in your preview, you can cite this sample user:
struct ProfileFeedView_Previews: PreviewProvider {
static var previews: some View {
ProfileFeedView(user: User.example)
}
}