Explicitly Set Core Data Objects Still Carry Nil Value - ios

Question

Working through Paul Hudson's "100 Days of SwiftUI" and I'm having an issue where data from a FetchRequest features nil values for some properties even after they've been set explicity.
The idea is fire off a request for a .json file, download it, and then parse it into some CoreData objects.
Here's the output:
And clicking on the top "Unknown" yields:
Now for some code:
ContentView
import SwiftUI
struct ContentView: View {
#Environment(\.managedObjectContext) var moc
#FetchRequest(sortDescriptors: []) var cachedUsers: FetchedResults<CachedUser>
#State private var users = [User]()
var body: some View {
NavigationView {
List(cachedUsers) { cachedUser in
NavigationLink {
VStack(alignment: .leading){
Text("Name: \(cachedUser.unwrappedName)")
.font(.largeTitle)
Spacer()
Section {
Text("Email:")
Text(cachedUser.uEmail)
.font(.body)
.foregroundColor(.secondary)
Text("Company")
Text(cachedUser.uCompany)
.font(.body)
.foregroundColor(.secondary)
Text("Address:")
Text(cachedUser.uAddress)
.font(.body)
.foregroundColor(.secondary)
} header: {
Text("Contact")
.font(.title)
}
Spacer()
Spacer()
}
} label: {
VStack(alignment: .leading){
Text("\(cachedUser.unwrappedName)")
.font(.headline)
.foregroundColor(cachedUser.isActive ? .white : .red)
}
}
}
.task {
if cachedUsers.isEmpty {
do {
if let retrievedUsers = try await loadData() {
users = retrievedUsers
}
} catch {
print(error)
}
await MainActor.run {
saveToCoreData(users: users)
}
}
printCache()
}
.navigationTitle("Users")
.foregroundColor(.white)
}
.navigationViewStyle(StackNavigationViewStyle())
}
func loadData() async throws -> [User]? {
if users.isEmpty {
let targetURL = "https://www.hackingwithswift.com/samples/friendface.json"
guard let url = URL(string: targetURL) else {
print("Bad URL. No biscuit.")
return users
}
let (data, _) = try await URLSession.shared.data(from: url)
do {
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .iso8601
users = try decoder.decode([User].self, from: data)
} catch {
print(error)
}
}
return users
}
func saveToCoreData(users: [User]){
for user in users {
let cd = CachedUser(context: moc)
cd.about = user.about
cd.address = user.address
cd.age = Int16(user.age)
cd.company = user.company
cd.email = user.email
cd.id = user.id
cd.isActive = user.isActive
cd.name = user.name
cd.registered = user.registered
for friend in user.friends {
let cf = CachedFriend(context: moc)
cf.id = friend.id
cf.name = friend.name
cd.addToFriend(cf)
}
do {
if moc.hasChanges {
try moc.save()
}
} catch {
print(error)
}
}
}
func printCache() {
for cachedUser in cachedUsers {
print("Name: \(cachedUser.unwrappedName) | \(cachedUser.uUUID) ")
}
}
}
User
import Foundation
struct User: Codable, Identifiable {
enum CodingKeys: CodingKey {
case id, isActive, name, age, company, email, address, about, registered, tags, friends
}
var id = UUID()
var isActive: Bool = false
var name: String = ""
var age: Int16 = 20
var company: String = ""
var email: String = ""
var address: String = ""
var about: String = ""
var registered: Date = Date.now
var tags: [String] = []
var friends: [Friend] = []
init() { }
func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(id, forKey: .id)
try container.encode(isActive, forKey: .isActive)
try container.encode(name, forKey: .name)
try container.encode(age, forKey: .age)
try container.encode(company, forKey: .company)
try container.encode(email, forKey: .email)
try container.encode(address, forKey: .address)
try container.encode(about,forKey: .about)
try container.encode(registered,forKey: .registered)
try container.encode(tags, forKey: .tags)
try container.encode(friends, forKey: .friends)
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
id = try container.decode(UUID.self, forKey: .id)
isActive = try container.decode(Bool.self, forKey: .isActive)
name = try container.decode(String.self, forKey: .name)
age = try container.decode(Int16.self, forKey: .age)
company = try container.decode(String.self, forKey: .company)
email = try container.decode(String.self, forKey: .email)
address = try container.decode(String.self, forKey: .address)
about = try container.decode(String.self, forKey: .about)
registered = try container.decode(Date.self, forKey: .registered)
tags = try container.decode([String].self, forKey: .tags)
friends = try container.decode([Friend].self, forKey: .friends)
}
}
class UserData: ObservableObject, Codable {
#Published var user = User()
enum CodingKeys: CodingKey {
case user
}
init() { }
func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(user, forKey: .user)
}
required init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
user = try container.decode(User.self, forKey: .user)
}
}
NOTE: The CachedUser extension handles name and email (for example) identically.
Core Data Entity and printCache() Result Screenshot
It doesn't make any sense at all how printCache (which is going through the FetchResults cachedUsers objects) can print names, but then the minute I go through that exact same fetch object only the names don't carry through ("Unknown" displays as a result of nil coelescing) , but all the other data (About section, email, company, address) somehow does. The CachedFriend names don't, but I suspect that's the same issue I'm having with the CachedUser object just downstream.

Answer 1

So I discovered that the users are getting added after all. I realized that when I went to scroll on all my 'Unknowns' if I scrolled down far enough (1000+ rows) I'd start to see names. I have no idea what I did, but at one point I was adding to CoreData without regard to replacement.
In the end I had to tweak loadData() a little to get this working and then delete a bunch of garbage data that had gone in during the process of development. The ContentView was the only place I was doing it wrong. All the other code was fine.
**UPDATED ContentView (Working) **
import SwiftUI
struct ContentView: View {
#Environment(\.managedObjectContext) var moc
#FetchRequest(sortDescriptors: []) var cachedUsers: FetchedResults<CachedUser>
#State private var users = [User]()
var body: some View {
NavigationView {
List {
ForEach(cachedUsers) { cachedUser in
NavigationLink {
VStack(alignment: .leading){
//... same as above
} header: {
Text("Contact")
.font(.title)
}
Spacer()
Spacer()
}
} label: {
VStack(alignment: .leading){
Text("\(cachedUser.uName)")
.font(.headline)
.foregroundColor(cachedUser.isActive ? .white : .red)
}
}
}
.onDelete(perform: removeUser)
}
.task {
await loadData()
}
.toolbar {
EditButton()
}
.navigationTitle("Users")
.foregroundColor(.white)
}
.navigationViewStyle(StackNavigationViewStyle())
}
func removeUser(at offsets: IndexSet) {
for index in offsets {
//this hack helped me tremendously in cleaning up the CoreData object. I was adding 200 to the index at one point.
//for i in index...index + 10{
let user = cachedUsers[index]
moc.delete(user)
do {
try moc.save()
} catch {
print(error)
}
//}
}
}
func loadData() async {
if cachedUsers.isEmpty {
let targetURL = "https://www.hackingwithswift.com/samples/friendface.json"
guard let url = URL(string: targetURL) else {
print("Bad URL. No biscuit.")
return
}
do {
let (data, _) = try await URLSession.shared.data(from: url)
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .iso8601
users = try decoder.decode([User].self, from: data)
await MainActor.run {
saveToCoreData(users: users)
}
} catch {
print(error)
}
}
}
func saveToCoreData(users: [User]){
for user in users {
let cd = CachedUser(context: moc)
cd.about = user.about
cd.address = user.address
cd.age = Int16(user.age)
cd.company = user.company
cd.email = user.email
cd.id = user.id
cd.isActive = user.isActive
cd.name = user.name
cd.registered = user.registered
for friend in user.friends {
let cf = CachedFriend(context: moc)
cf.id = friend.id
cf.name = friend.name
cd.addToFriend(cf)
}
do {
if moc.hasChanges {
try moc.save()
}
} catch {
print(error)
}
}
}
}