ios - Swift Firebase 检查认证更顺畅

Question

我立即将窗口的 Root View Controller 设置为登录 Controller ，登录 Controller 检查来自 Firebase 的用户身份验证。如果用户登录， Controller 将 Root View Controller 更改为提要 Controller 。否则，登录 Controller 将自行处理。

class LoginController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        if let uid = Auth.auth().currentUser?.uid {

            Database.database().reference().child("users").observeSingleEvent(of: .value, with: { snapshot in
                if snapshot.hasChild(uid) {
                    AppDelegate.launchApplication()
                }
                else {
                    self.setUpUI()
                }
            })

        }
        else {
            self.setUpUI()
        }

    }
...
}

launchApplication 在哪里

class func launchApplication() {
    guard let window = UIApplication.shared.keyWindow else { return }
    window.rootViewController = UINavigationController(rootViewController: FeedController())
}

除了 if let uid = Auth.auth().currentUser?.uid，我还在检查 uid(如果不是 nil)存在于我的数据库中，因为我遇到过已删除用户仍然不是 nil 的情况。

问题是在启动屏幕完成后，有一段时间登录 Controller 是可见的，尽管它是空白的。有时这一刻会持续几秒钟。我如何检查身份验证以使登录 Controller 完全不可见——以便应用程序决定如何在启动屏幕消失后立即继续？谢谢。

Answer 1

1) 如果您想从 app delegate 本身设置 rootController，请使用以下代码。如果您的 currentUser.uid 不为 nil 并与数据库中的值匹配，请使用检查，然后在 Appdelegate 的 DidFinishLaunchingWithOptions 中执行以下代码。我用过

            func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.

    FirebaseApp.configure()
    GIDSignIn.sharedInstance().clientID = FirebaseApp.app()?.options.clientID



    if let uid = Auth.auth().currentUser?.uid {

        Database.database().reference().child("users").child(uid).observeSingleEvent(of: .value, with: { snapshot in
            if snapshot.exist() {
                let storyBoard = UIStoryboard.init(name: "Main", bundle: nil)
                let vc = storyBoard.instantiateViewController(withIdentifier: "feedController") as! FeedController

                self.window?.rootViewController=vc
                self.window?.makeKeyAndVisible()
            }
            else {
                //Present your loginController here
            }
        })

    }

    return true
}

2) 方法:当您初始化登录 Controller 而不是从 Appdelegate 或 LaunchApplication 中的代码调用函数时。在login类中创建一个函数，当需要的参数匹配时，编写如下代码

 var transition: UIViewAnimationOptions = .transitionFlipFromLeft
let rootviewcontroller: UIWindow = ((UIApplication.shared.delegate?.window)!)!
        rootviewcontroller.rootViewController = self.storyboard?.instantiateViewController(withIdentifier: "rootnav")//rootnav is Storyboard id of my naviagtionController attached to the DestinationController [FeedController]
        let mainwindow = (UIApplication.shared.delegate?.window!)!
        mainwindow.backgroundColor = UIColor(hue: 0.6477, saturation: 0.6314, brightness: 0.6077, alpha: 0.8)
        UIView.transition(with: mainwindow, duration: 0.55001, options: transition, animations: { () -> Void in
        }) { (finished) -> Void in

        }