为问题的模棱两可表示歉意； 我在这里尽量解释得更清楚些。
我在AppDelegate.swift中有一些执行条件导航的代码； 如果用户已登录（因此CurrentUser不是Nil)，则应用程序将在View中启动，这是Main情节提要中的一个视图控制器。 否则，如果用户没有登录，应用程序将在welcome中启动，这是auth情节提要中的一个视图控制器。
以下是我在AppDelegate.swift，ViewController.swift（即View)和WelcomeViewController中的代码。
注意:
View是我为ViewController设置的情节提要ID； welcomeViewController是我为WelcomeViewController设置的情节提要ID。
AppDelegate.swift
import UIKit
import Firebase
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Configures the Firebase library.
FirebaseApp.configure()
// Performs conditional navigation on the condition of currentUser's status.
self.window = UIWindow(frame: UIScreen.main.bounds)
let user = Auth.auth().currentUser
if user != nil {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let rootViewController = storyboard.instantiateViewController(identifier: "View")
window?.rootViewController = rootViewController
UIView.animate(withDuration: 0.5) {
self.window?.makeKeyAndVisible()
}
} else {
let storyboard = UIStoryboard(name: "Auth", bundle: nil)
let rootViewController = storyboard.instantiateViewController(identifier: "Welcome")
window?.rootViewController = rootViewController
UIView.animate(withDuration: 0.5) {
self.window?.makeKeyAndVisible()
}
}
return true
}
}
ViewController.swift
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
print("ViewController presented.")
}
}
WelcomeViewController.swift
import UIKit
class WelcomeViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
print("WelcomeViewController presented.")
}
}
该应用程序是新安装在模拟器上的，因此应该没有CurrentUser（在调试时，证明是真的）。 因此，我希望在控制台中看到以下输出:
WelcomeViewController presented.
相反，它显示在控制台中:
WelcomeViewController presented.
ViewController presented.
到目前为止，我认为问题可能是由于main情节提要是自项目创建以来的默认情节提要集这一事实引起的。 因此，我尝试取消选中两个视图控制器的‘初始视图控制器’复选框。 正如我所预料的那样，下面显示了以下内容:
WelcomeViewController presented.
2020-06-20 11:39:38.724658+0800 AppName[11439:237509] [WindowScene] Failed to instantiate the default view controller for UIMainStoryboardFile 'Main' - perhaps the designated entry point is not set?
如何确保ViewController不出现并替换WelcomeViewController？ 感谢所有的帮助，谢谢！
为什么不将WelcomeViewController设置为“初始视图控制器”并将其viewDidLoad代码替换为AppDelegate文件，然后:
class WelcomeViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
print("WelcomeViewController presented.")
let user = Auth.auth().currentUser
if user != nil {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let rootViewController = storyboard.instantiateViewController(identifier: "View")
window?.rootViewController = rootViewController
UIView.animate(withDuration: 0.5) {
self.window?.makeKeyAndVisible()
}
}
}
}
如果要从AppDelegate设置视图控制器，也可以查看以下内容:
编辑:您可以使用UINavigationController作为初始视图控制器，如以下答案所示:
在appdelegate-swift中设置初始viewcontroller，然后您只需在此处设置正确的view controller:
navigationController.viewControllers = [rootViewController]
self.window?.rootViewController = navigationController
我设法找到了我现在面临的问题的解决办法。 代码上面有两个错误，我在这里解释一下:
Xcode11与iOS13一起推出了SceneDelegate.swift。 我应该将上面的代码放在SceneDelegate.swift中，而不是AppDelegate.swift中； 因为我没有这样做，代码并没有像我所希望的那样运行在运行iOS13.5的模拟器。
以下是我在SceneDelegate.swift中修改的代码:
import UIKit
import Firebase
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
var window: UIWindow?
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
// Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
// If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
// This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
guard let _ = (scene as? UIWindowScene) else { return }
// Performs conditional navigation on the condition of currentUser's status.
let user = Auth.auth().currentUser
if user != nil {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let rootViewController = storyboard.instantiateViewController(identifier: "View")
window?.rootViewController = rootViewController
UIView.animate(withDuration: 0.5) {
self.window?.makeKeyAndVisible()
}
} else {
let storyboard = UIStoryboard(name: "Auth", bundle: nil)
let rootViewController = storyboard.instantiateViewController(identifier: "Welcome")
window?.rootViewController = rootViewController
UIView.animate(withDuration: 0.5) {
self.window?.makeKeyAndVisible()
}
}
}
}
在我上面的代码中，有一个错误行导致创建了一个新的UIWindow:
self.window = UIWindow(frame: UIScreen.main.bounds)
通过删除这一行代码，问题就解决了。 以下是修正后的代码:
let user = Auth.auth().currentUser
if user != nil {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let rootViewController = storyboard.instantiateViewController(identifier: "View")
window?.rootViewController = rootViewController
UIView.animate(withDuration: 0.5) {
self.window?.makeKeyAndVisible()
}
} else {
let storyboard = UIStoryboard(name: "Auth", bundle: nil)
let rootViewController = storyboard.instantiateViewController(identifier: "Welcome")
window?.rootViewController = rootViewController
UIView.animate(withDuration: 0.5) {
self.window?.makeKeyAndVisible()
}
}
我希望这对其他面临这个问题的人有帮助！
