How to set the default SyncConfiguration for Realm, so I can get it in multiple ViewControlllers without redundant code?

Question

According to the:

• Proper Realm usage patterns/best practices
• What is the best practice or design pattern to maintain sync activity across multiple views
• Design Pattern for Realm Database Swift 3.1 - Singleton

my approach is like:

AppDelegate.swift

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
    DispatchQueue.main.async {
        let username = "test@test.com"
        let password = "Test123"
        let serverUrl = URL(string: "http://test.com:9080")
        let realmUrl = URL(string: "realm://test.com:9080/~/realmtest")

        if let user = SyncUser.current {
            Realm.Configuration.defaultConfiguration.syncConfiguration = SyncConfiguration(user: user, realmURL: realmUrl!)
        } else {
            SyncUser.logIn(with: .usernamePassword(username: username, password: password, register: false), server: serverUrl!, onCompletion: { (user, error) in
                guard let user = user else {
                    print("Error: \(String(describing: error?.localizedDescription))")
                    return
                }
                Realm.Configuration.defaultConfiguration.syncConfiguration = SyncConfiguration(user: user, realmURL: realmUrl!)
            })
        }
    }

    return true
}

ViewController.swift

override func viewDidLoad() {
    super.viewDidLoad()
    print("SyncConfiguration: \(String(describing: Realm.Configuration.defaultConfiguration.syncConfiguration))")
    self.realm = try! Realm()
}

When I open app for the first time nothing happens but when I open app the second time, Realm works fine.

Whenever I open app, the printed SyncConfiguration is nil. No errors!

Searched here and there and can't find an answer...

Answer 1

The problem is that you are using an async method to configure your Realm, but you don't call the print inside the completion handler of your method. You should only present your viewcontoller once your asynchronous call has finished.