Segue没有被执行

Question

在我的第一个ViewController中，我正在检查用户是否已使用Firebase登录，如果他/她是，则重定向到主交换机，如果没有，则重定向到登录视图。但是，欢迎视图只保留在视图中，不会发生重定向。

import UIKit
import Firebase

class WelcomeVC: UIViewController {

    @IBOutlet weak var btnLogin: RoundedShadowButton!

    override func viewDidLoad() {
        super.viewDidLoad()

        if(Auth.auth().currentUser?.uid != nil) {
            //user is logged in
            performSegue(withIdentifier: "goToSwitchboardVC", sender: self)
        }
        else {
            //user in not logged in
            performSegue(withIdentifier: "goToLoginVC", sender: self)
        }
    }

    @IBAction func btnLoginWasPressed(_ sender: Any) {
        performSegue(withIdentifier: "goToLoginVC", sender: self)
    }

}

代码已更改

import UIKit
import Firebase

class WelcomeVC: UIViewController {

    @IBOutlet weak var btnLogin: RoundedShadowButton!

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    override func viewWillAppear(_ animated: Bool) {
        print("AUTH USER")
        print(Auth.auth().currentUser)
        print(Auth.auth().currentUser?.uid)

        if(Auth.auth().currentUser?.uid != nil) {
            //user is logged in
            performSegue(withIdentifier: "goToSwitchboardVC", sender: self)
        }
        else {
            //user in not logged in
            performSegue(withIdentifier: "goToLoginVC", sender: self)
        }
    }

    @IBAction func btnLoginWasPressed(_ sender: Any) {
        performSegue(withIdentifier: "goToLoginVC", sender: self)
    }

}

Answer 1

您的代码不会重定向到任何视图，因为您已在viewWillAppear中编写它。在视图出现之前无法执行Segue所以你必须在viewDidAppear中执行segue。如果其他一切都正确（segue名称和连接），那么它肯定会起作用。

试试这个 -

override func viewDidAppear(_ animated: Bool) {
    print("AUTH USER")
    print(Auth.auth().currentUser)
    print(Auth.auth().currentUser?.uid)

    if(Auth.auth().currentUser?.uid != nil) {
        //user is logged in
        performSegue(withIdentifier: "goToSwitchboardVC", sender: self)
    }
    else {
        //user in not logged in
        performSegue(withIdentifier: "goToLoginVC", sender: self)
    }
}

Answer 2

确保故事板中有正确连接的segue，并且segue的名称已正确设置为“goToLoginVC”。

另外请提供点击连接到btnLoginWasPressed动作的按钮的结果，以验证segue在那种情况下工作，而不是在你的viewDidLoad函数中。