Persist auth data & recover it case DB gets corrupted or destroyed

Rocket.Chat/Controllers/MainViewController.swift

@@ -25,6 +25,11 @@ final class MainViewController: BaseViewController {
         }
     }
 
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        AuthManager.recoverAuthIfNeeded()
+    }
+
     override func viewDidAppear(_ animated: Bool) {
         super.viewDidAppear(animated)
 
@@ -37,6 +42,8 @@ final class MainViewController: BaseViewController {
         super.viewWillAppear(animated)
 
         if let auth = AuthManager.isAuthenticated() {
+            AuthManager.persistAuthInformation(auth)
+
             labelAuthenticationStatus.isHidden = true
             buttonConnect.isHidden = true
             activityIndicator.startAnimating()

Rocket.Chat/Managers/Model/AuthManager.swift

@@ -9,7 +9,14 @@
 import Foundation
 import RealmSwift
 
+struct AuthManagerPersistKeys {
+    static let token = "kAuthToken"
+    static let serverURL = "kAuthServerURL"
+    static let userId = "kUserId"
+}
+
 struct AuthManager {
+
     /**
         - returns: Last auth object (sorted by lastAccess), if exists.
     */
@@ -26,6 +33,47 @@ struct AuthManager {
         guard let user = try? Realm().object(ofType: User.self, forPrimaryKey: auth.userId) else { return nil }
         return user
     }
+
+    /**
+        This method is going to persist the authentication informations
+        that was latest used in NSUserDefaults to keep it safe if something
+        goes wrong on database migration.
+     */
+    static func persistAuthInformation(_ auth: Auth) {
+        let defaults = UserDefaults.standard
+        defaults.set(auth.token, forKey: AuthManagerPersistKeys.token)
+        defaults.set(auth.serverURL, forKey: AuthManagerPersistKeys.serverURL)
+        defaults.set(auth.userId, forKey: AuthManagerPersistKeys.userId)
+    }
+
+    static func recoverAuthIfNeeded() {
+        if AuthManager.isAuthenticated() != nil {
+            return
+        }
+
+        guard
+            let token = UserDefaults.standard.string(forKey: AuthManagerPersistKeys.token),
+            let serverURL = UserDefaults.standard.string(forKey: AuthManagerPersistKeys.serverURL),
+            let userId = UserDefaults.standard.string(forKey: AuthManagerPersistKeys.userId) else {
+                return
+        }
+
+        Realm.executeOnMainThread({ (realm) in
+            // Clear database
+            realm.deleteAll()
+
+            let auth = Auth()
+            auth.lastSubscriptionFetch = nil
+            auth.lastAccess = Date()
+            auth.serverURL = serverURL
+            auth.token = token
+            auth.userId = userId
+
+            PushManager.updatePushToken()
+
+            realm.add(auth)
+        })
+    }
 }
 
 // MARK: Socket Management
@@ -214,6 +262,11 @@ extension AuthManager {
             SocketManager.clear()
             GIDSignIn.sharedInstance().signOut()
 
+            let defaults = UserDefaults.standard
+            defaults.removeObject(forKey: AuthManagerPersistKeys.token)
+            defaults.removeObject(forKey: AuthManagerPersistKeys.serverURL)
+            defaults.removeObject(forKey: AuthManagerPersistKeys.userId)
+
             Realm.executeOnMainThread({ (realm) in
                 realm.deleteAll()
             })