use helper method to fetch specific attribute from core data - swift

Question

IN my swift 5 code below the goal would be to fetch the first item from core data entity Info attribute username. I am attempting to d that right now I am getting a error at titleLabel.text = String(user![0]) stating
no exact matches in call to initializer
Somehow I know I will need to attach .username somehow but I dont know what to do next at this point.
class ViewController: UIViewController {
var user : [User]? = nil
var titleLabel = UILabel()
override func viewDidLoad() {
super.viewDidLoad()
user = CoredataHandler.fetchObject()
titleLabel.text = String(user![0])
}
}
class CoredataHandler : NSManagedObject {
private class func getContext() -> NSManagedObjectContext {
let appDelegate = UIApplication.shared.delegate as! AppDelegate
return appDelegate.persistentContainer.viewContext
}
class func saveObject(username: String,password: String,tf: Bool) -> Bool{
let context = getContext()
let entity = NSEntityDescription.entity(forEntityName: "User", in: context)
let managedObject = NSManagedObject(entity: entity!, insertInto: context)
managedObject.setValue(username, forKey: "username")
managedObject.setValue(password, forKey: "password")
managedObject.setValue(tf, forKey: "tf")
do {
try context.save()
return true
} catch{
return false
}
}
class func fetchObject() -> [User]?
{
let context = getContext()
var user : [User]? = nil
do {
user = try context.fetch(User.fetchRequest())
return user
} catch {
return user
}
}
}