Make a relationship with FirebaseAuth

Firebase User

Install Firebase/Auth with CocoaPods.

pod 'Pring'
pod 'Firebase/Auth'

User Scheme

extension Firebase {
    @objcMembers
    class User: Object {

        dynamic var name: String = ""

        // MARK: -
        static let loggedInNotification: NSNotification.Name = NSNotification.Name(rawValue: "loggedInNotification")

        static let loggedOutNotification: NSNotification.Name = NSNotification.Name(rawValue: "loggedOutNotification")

        @discardableResult
        func signup(_ block: ((DocumentReference?, Error?) -> Void)? = nil) -> [String : StorageUploadTask] {
            return save { (ref, error) in
                if let error = error {
                    block?(nil, error)
                    return
                }
                NotificationCenter.default.post(name: User.loggedInNotification, object: ref)
                block?(ref, nil)
            }
        }

        class func loggedIn(_ block: @escaping () -> Void) -> NSObjectProtocol {
            return NotificationCenter.default.addObserver(forName: User.loggedInNotification, object: nil, queue: .main) { (notification) in
                print("login")
                block()
            }
        }

        class func loggedOut(_ block: @escaping () -> Void) -> AuthStateDidChangeListenerHandle {
            return Auth.auth().addStateDidChangeListener { (auth, user) in
                if user == nil {
                    print("logout")
                    block()
                }
            }
        }
    }
}

extension Firebase.User {

    /// Return current user
    ///
    /// - Parameters:
    /// - completion: 
    static func current(_ completionHandler: @escaping ((Firebase.User?) -> Void)) {
        guard let user: User = Auth.auth().currentUser else {
            completionHandler(nil)
            return
        }
        Firebase.User.get(user.uid) { (user, _) in
            guard let user: Firebase.User = user else {
                // Log out if the user is not saved in Firebase DB
                _ = try? Auth.auth().signOut()
                completionHandler(nil)
                return
            }
            completionHandler(user)
        }
    }
}

Make relationship with Auth

Auth.auth().signInAnonymously { (user, error) in
    if let error: Error = error {
        print(error)
        return
    }
    let user: Firebase.User = Firebase.User(id: user!.uid)
    user.name = "USER_NAME"
    user.signup()
}

Retrieve login user

Firebase.User.current { [weak self](user) in
    guard let user: Firebase.User = user else {
        return
    }
    guard let `self` = self else { return }
    // Do something
}