Cache implementation method - swift

Question

I want to save as cache as UserDefaults.
But,
This is signupButtonTapped:
#IBAction private func signUpButtonTapped(_ sender: Any) {
KRProgressHUD.show(withMessage: "loading")
Authentication.signUp(
name: nameTextField.text!, // "new"
email: emailTextField.text!, // "new"
password: passwordTextField.text!, // "new"
image: selectedImage,
onSuccess: {
KRProgressHUD.dismiss()
API.User.getCurrentUser { (user) in
CurrentUser.shared.synchronize(user: user)
}
self.presentViewController()
}) { (error) in
KRProgressHUD.showError(withMessage: "\(error!)")
}
}
this is CurrentUser class:
import Foundation
final class CurrentUser: User {
// Get
static let shared: CurrentUser = {
let user = CurrentUser()
let userDefaults = UserDefaults.standard
user.userID = userDefaults.string(forKey: userID_field)
user.name = userDefaults.string(forKey: name_field)
user.email = userDefaults.string(forKey: email_field)
return user
}()
// Save
func synchronize(user: user) {
print(user.name, user.userID, user.email) // "new", "new", "new"
// <<<< BREAKPOINT
let userDefaults = UserDefaults.standard
userDefaults.set(user.userID, forKey: userID_field)
userDefaults.set(user.name, forKey: name_field)
userDefaults.set(user.email, forKey: email_field)
print(userDefaults.string(forKey: name_field), userDefaults.string(forKey: userID_field), userDefaults.string(forKey: email_field)) // "new", "new", "new"
print(CurrentUser.shared.name, CurrentUser.shared.userID, CurrentUser.shared.email) // "old", "old", "old"
// <<<< BREAKPOINT
}
I want the last print(CurrentUser.shared.ooo) function to be "new", "new", "new".
However, the old value "old" is displayed instead.
What is wrong with my cache implementation?

Answer 1

Since you are using static instance shared that property will only hold the first value. You need to change your strategy to something else, because once your app is launched the computed property won't compute again and thus won't fetch data from userdefaults.
You see when you save your new data and then quit and launch your app again it should display the expected result, but since you are trying to get the data when your app is launched it will obviously display the previously stored one. A simple solution would be to not user shared instance for this, you could do something like following:
//Put the currentUser in User class
class User {
var userID = ""
var name = ""
var email = ""
class var current: User {
let user = User()
let defaults = UserDefaults.standard
user.email = defaults.string(forKey: email_field) ?? "" //this can be nil if no data
user.userID = defaults.string(forKey: userID_field) ?? ""
user.name = defaults.string(forKey: name_field) ?? ""
return user
}
func synchronize() {
let userDefaults = UserDefaults.standard
userDefaults.set(self.userID, forKey: userID_field)
userDefaults.set(self.name, forKey: name_field)
userDefaults.set(self.email, forKey: email_field)
print(userDefaults.string(forKey: name_field), userDefaults.string(forKey: userID_field), userDefaults.string(forKey: email_field))
print(User.current.name, User.current.userID, User.current.email)
}
}
Now you can perform your operations. Like so
let newUser = User()
newUser.userID = "123"
....
newUser.synchronize() //save
//When you need current user
User.current