如何检查当前用户是否存在？

Question

我使用以下代码检查用户是否存在然后从数据库中检索数据，否则什么也不做，但是当应用程序加载并且用户不存在时（我是用户）它执行数据库查询给出了

的错误

在展开可选值时意外发现 nil：文件

在这一行

self.checksetup = document.get("setupComplete") as！布尔

这不应该发生，因为用户不存在，我在 Swift IOS 中使用它并使用 Firestore 数据库和 firebase 身份验证

override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        let user1: User = Auth.auth().currentUser!
        if let user: User = Auth.auth().currentUser! {
            let setupcheckref = Firestore.firestore().collection("users").document(Auth.auth().currentUser!.uid)
            setupcheckref.getDocument{(document, error) in
                if let document = document, document.exists{
                    let dataDescription = document.data().map(String.init(describing:)) ?? "nil"

                    self.checksetup = document.get("setupComplete") as! Bool

                    if self.checksetup == true {
                        if Auth.auth().currentUser!.isEmailVerified {
                                           self.performSegue(withIdentifier: "toHomeScreen", sender: self)
                                           SVProgressHUD.dismiss()
                                       }
                                       else{
                                           print("please verify your email")
                                           try! Auth.auth().signOut()

                                           let alertController = UIAlertController(title: "Email Verification", message:
                                               "Please verify your email to Login! Check Your Inbox!", preferredStyle: .alert)
                                           alertController.addAction(UIAlertAction(title: "Dismiss", style: .default))

                                           self.present(alertController, animated: true, completion: nil)
                                          // self.view.makeToast("please verify your email")
                                           self.sendEmailVerification()
                                           SVProgressHUD.dismiss()
                                       }

                    }

                    else{

                        self.view.makeToast("Please Setup Your Account!", duration: 2.5)


                        self.performSegue(withIdentifier: "tocompletesetup", sender: self)
                        SVProgressHUD.dismiss()
                    } }

            }

           // self.performSegue(withIdentifier: "toHomeScreen", sender: self)
        }



    }

Answer 1

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    guard let user: User = Auth.auth().currentUser else {
        view.makeToast("Please Setup Your Account!", duration: 2.5)
        performSegue(withIdentifier: "tocompletesetup", sender: self)
        SVProgressHUD.dismiss()
        return
    }
    let setupcheckref = Firestore.firestore().collection("users").document(user.uid)
    setupcheckref.getDocument { document, _ in
        if let document = document, document.exists {
            let dataDescription = document.data().map(String.init(describing:)) ?? "nil"
            if self.checksetup = document.get("setupComplete") as? Bool, self.checksetup {
                if user.isEmailVerified {
                    self.performSegue(withIdentifier: "toHomeScreen", sender: self)
                    SVProgressHUD.dismiss()
                } else {
                    print("please verify your email")
                    do {
                        try? Auth.auth().signOut()
                        let alertController = UIAlertController(title: "Email Verification", message:
                            "Please verify your email to Login! Check Your Inbox!", preferredStyle: .alert)
                        alertController.addAction(UIAlertAction(title: "Dismiss", style: .default))

                        self.present(alertController, animated: true, completion: nil)
                        // self.view.makeToast("please verify your email")
                        self.sendEmailVerification()
                        SVProgressHUD.dismiss()
                    } catch {}
                }
            } else {
                print("check failed",self.checksetup)
            }
        } else {
            print("Document doesnt exists")
        }
    }
}