Check userDefaults in Swift/Xcode for 'User()'

User.swift

class User: Codable {

    static let shared = User()
    var hasBeenUpdated = false
    var completedTasks: Int = 0
    var currentlyViewingTask: Int = 0
    var milestoneNumber: Int = 0
    var totalMilestones: Int = 0 
    var milestones: [Int] = [1,2,5,10,20,40]
    var canEdit: Bool = false 

}

ViewController.swift

class ViewController: UIViewController {
    
    func checkUserDefaults() {
            var user = User.shared
            let userData = "userData"
            if let dataUser = userDefaults.data(forKey: userData) {
                let decoder = JSONDecoder()
                do {
                    self.user = try decoder.decode(User.self, from: dataUser)
                } catch {
                    fatalError("fatalError: \(error)")
                }
            }
        }   
    }