Updating a codable user struct - swift

Question

I'm developing an app where the user can create up to 5 profiles when I came across a problem.
Problem:
Fatal error: Unexpectedly found nil while unwrapping an Optional value: file
Info:
The first edition of the app has a struct with these data points in it:
id
profileName
profileIcon
When the app opens it loads the user via func loadUser()
Now, during an update I've added a new data point in the user struct so it now looks like this:
id
profileName
profileIcon
profileSummary
Now when the func loadUser() is called it fails with this statement:
Fatal error: Unexpectedly found nil while unwrapping an Optional value: file
How the system is built:
When the app is opened the first time it creates 5 empty profiles. The user can then "activate" and fill out these profiles and he/she likes.
I'm a little uncertain how to deal with this problem. How can I add new data points to my struct without causing the app to crash?
Source code:
struct User: Codable {
// Core user data
let id: Int
var profileName: String
var profileIcon: String
var profileSummary: String
}
class DataManager: NSObject {
/// Used to encode and save user to UserDefaults
func saveUser(_ user: User) {
if let encoded = try? JSONEncoder().encode(user) {
UserDefaults.standard.set(encoded, forKey: "userProfile_\(user.id)")
print("Saved user (ID: \(user.id)) successfully.")
}
}
/// Used to decode and load user from UserDefaults
func loadUser(_ userID: Int) -> User {
var user : User?
if let userData = UserDefaults.standard.data(forKey: "userProfile_\(userID)"),
let userFile = try? JSONDecoder().decode(User.self, from: userData) {
user = userFile
print("Loaded user (ID: \(user!.id)) successfully.")
}
return user!
}
/// Used to create x empty userprofiles ready to be used
func createEmptyProfiles() {
// May be changed, but remember to adjust UI
var profilesAllowed = 5
while profilesAllowed != 0 {
print("Attempting to create empty profile for user with ID \(profilesAllowed)")
let user = User(id: profilesAllowed, profileName: "", profileIcon: "", profileSummary: "Write a bit about your profile here..")
self.saveUser(user)
print("User with ID \(profilesAllowed) was created and saved successfully")
// Substract one
profilesAllowed -= 1
}
}
//MARK: - Delete profile
func deleteUser(user: User) -> Bool {
var userHasBeenDeleted = false
var userToDelete = user
// Reset all values
userToDelete.profileName = ""
userToDelete.profileIcon = ""
userToDelete.profileSummary = ""
// Save the resetted user
if let encoded = try? JSONEncoder().encode(userToDelete) {
UserDefaults.standard.set(encoded, forKey: "userProfile_\(user.id)")
print("User has now been deleted")
userHasBeenDeleted = true
}
return userHasBeenDeleted
}
}

Answer 1

Two options:
Make profileSummary optional
struct User: Codable {
// Core user data
let id: Int
var profileName: String
var profileIcon: String
var profileSummary: String?
}
If the key doesn't exist it will be ignored.
Implement init(from decoder) and decode profileSummary with decodeIfPresent assigning an empty string if it isn't.
Side note:
Never try? in a Codable context. Catch the error and handle it. Your loadUser method crashes reliably if an error occurs. A safe way is to make the method throw and hand over errors to the caller.
enum ProfileError : Error { case profileNotAvailable }
/// Used to decode and load user from UserDefaults
func loadUser(_ userID: Int) throws -> User {
guard let userData = UserDefaults.standard.data(forKey: "userProfile_\(userID)") else { throw ProfileError.profileNotAvailable }
return try JSONDecoder().decode(User.self, from: userData)
}