How to avoid using singleton in a proper way? - ios

Question

I want to refactor my code to apply clean approach.
I have a class user
class User {
let name: String?
let id: String
var isOnline: Bool
var mesaageHistory = [Message]()
init(name: String, id: String, isOnlineStatus: Bool) {
self.name = name
self.id = id
self.isOnline = isOnlineStatus
}
}
Then I'm using fabric pattern to create list of my users.
protocol CreateUserProtocol: class {
func sortArray(inputArr: [User])
}
class CreateUserEntity: CreateUserProtocol {
static let shared = CreateUserEntity()
var users = [User]()
func sortArray(inputArr: [User]){
var applySortingByDate: Bool = false
for user in inputArr {
if !user.mesaageHistory.isEmpty {
applySortingByDate = true
}
}
if applySortingByDate {
inputArr.sorted(by: { (first, second) -> Bool in
(first.mesaageHistory.last?.messageTime)! < (second.mesaageHistory.last?.messageTime)!
})
} else {
inputArr.sorted(by: { (first, second) -> Bool in
first.name! < second.name!
})
}
}
}
One controller is responsible for appending new users, while another is used to retrieve them and bind them to tableView. Everything is working fine, but I think my solution is not good enough for scaling.
Moreover in one of my VC I use to sort my Users to online and offline. I think, that I shouldn't do that in my VC and to put this logic into my CreateUserEntity
var onlineUsersData = [User]()
var offlineUsersData = [User]()
private func classifyUsers() {
for user in CreateUserEntity.shared.users {
print("is user online: \(user.isOnline)")
print(CreateUserEntity.shared.users.count)
if user.isOnline == true && !onlineUsersData.contains(user) {
onlineUsersData.append(user)
}
if user.isOnline == false && !offlineUsersData.contains(user) {
offlineUsersData.append(user)
}
}
}
I'd like to rewrite it in proper way, what can you recommend me?

Answer 1

From my opinion try to use firstly struct instead of the class.
Example:
struct User {
let name: String
}
Then you should figure out where you will be storing these users? Now they are in the memory. So we should define where and how we will be storing them.
So probably for this case we can consider NSUserDefaults as core for the class that will store users.After that we should create facade to this class to manage our users.
protocol UserStoreFacade {
func fetch(name withName:String) -> User
func create(name withName:String) -> User
func save(user:User)
func update(name newName:String) -> User
func delete(name withName:String)
}
And UserStore that is used to manage user.
class UserStore: UserStoreFacade {
let defaults = UserDefaults(suiteName: "User")
func fetch(name withName:String) -> User {
let encodeData = defaults?.dictionary(forKey: withName)
return User(dictionary: encodeData as! Dictionary<String, AnyObject>)
}
func create(name withName: String) -> User {
return User(name: withName)
}
func save(user: User) {
defaults?.set(user.encode(), forKey: user.name)
}
func update(name newName:String) -> User {
return User(name: newName)
}
func delete(name withName:String) {
defaults?.removeObject(forKey: withName)
}
}
It is quite primitive but still showing case how it is possible to accomplish.