使用Swift通过Firebase中的给定电子邮件获取用户的uid

import Firebase

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    FirebaseApp.configure()
    return true
}

import FirebaseAuth

func getUserUID(email: String, completion: @escaping (String?) -> Void) {
    Auth.auth().fetchSignInMethods(forEmail: email) { (methods, error) in
        if let error = error {
            print("Error fetching sign-in methods: \(error.localizedDescription)")
            completion(nil)
            return
        }
        
        if let methods = methods, methods.contains(EmailAuthProvider.emailPassword().providerID) {
            Auth.auth().signIn(withEmail: email, password: "password") { (result, error) in
                if let error = error {
                    print("Error signing in: \(error.localizedDescription)")
                    completion(nil)
                    return
                }
                
                if let uid = result?.user.uid {
                    completion(uid)
                } else {
                    completion(nil)
                }
            }
        } else {
            completion(nil)
        }
    }
}

let email = "example@example.com"
getUserUID(email: email) { (uid) in
    if let uid = uid {
        print("User uid: \(uid)")
    } else {
        print("Failed to get user uid")
    }
}