我解决不了.线程 1:致命错误:解开可选值时意外发现 nil

Question

前提

我目前正在使用 Swift 制作 SNS。 我在实现用户添加的功能时遇到了以下错误消息。

错误信息

Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value

代码雨燕4

import UIKit
class PeopleViewController: UIViewController {
@IBOutlet weak var tableView: UITableView!
var users = [UserModel]()
var userUid = ""
override func viewDidLoad() {
super.viewDidLoad()
tableView.dataSource = self
tableView.tableFooterView = UIView(frame: .zero)
tableView.rowHeight = 80
loadUser()
}
func loadUser() {
UserApi.shared.observeUser { (user) in
self.isFollowing(userUid: user.uid!, completed: { (value) in
**if user.uid != UserApi.shared.CURRENT_USER_UID! {**　<-errorPoint
user.isFollowing = value
self.users.append(user)
self.tableView.reloadData()
}
})
}
}

func isFollowing(userUid: String, completed: @escaping (Bool) -> Void ) {
FollowApi.shared.isFollowing(withUser: userUid, completed: completed)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "ShowUserInfoSegue" {
let showUserInfoVC = segue.destination as! ShowUserinfoViewController
showUserInfoVC.userUid = self.userUid
}
}
}
extension PeopleViewController: PeopleCellDelegate {
func didTappedShowUserInfo(userUid: String) {
self.userUid = userUid
performSegue(withIdentifier: "ShowUserInfoSegue", sender: self)
}
}

extension PeopleViewController: UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return users.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "PeopleTableViewCell", for: indexPath) as! PeopleTableViewCell
cell.user = users[indexPath.row]
cell.delegate = self
return cell
}
}

代码雨燕4

import Foundation
import FirebaseDatabase
import FirebaseAuth
class UserApi {
var REF_USERS = Database.database().reference().child("users")
static var shared: UserApi = UserApi()
private init() {
}
var CURRENT_USER_UID: String? {
if let currentUserUid = Auth.auth().currentUser?.uid {
return currentUserUid
}
return nil
}
var CURRENT_USER: User? {
if let currentUserUid = Auth.auth().currentUser {
return currentUserUid
}
return nil
}
func observeUser(uid: String, completion: @escaping (UserModel) -> Void) {
REF_USERS.child(uid).observeSingleEvent(of: .value) { (snapshot) in
guard let dic = snapshot.value as? [String: Any] else { return }
let newUser = UserModel(dictionary: dic)
completion(newUser)
}
}
func observeUser(completion: @escaping (UserModel) -> Void ) {
REF_USERS.observe(.childAdded) { (snapshot) in
guard let dic = snapshot.value as? [String: Any] else { return }
let user = UserModel(dictionary: dic)
completion(user)
}
}
func observeCurrentUser(completion: @escaping (UserModel) -> Void ) {
guard let currentUserUid = CURRENT_USER_UID else { return }
REF_USERS.child(currentUserUid).observeSingleEvent(of: .value) { (snapshot) in
guard let dic = snapshot.value as? [String: Any] else { return }
let currentUser = UserModel(dictionary: dic)
completion(currentUser)
}
}
func queryUser(withText text: String, completion: @escaping(UserModel) -> Void ) {
REF_USERS.queryOrdered(byChild: "username_lowercase").queryStarting(atValue: text).queryEnding(atValue: text + "u{f8ff}").queryLimited(toLast: 5).observeSingleEvent(of: .value) { (snapshot) in
snapshot.children.forEach({ (data) in
let child = data as! DataSnapshot
guard let dic = child.value as? [String: Any] else { return }
let user = UserModel(dictionary: dic)
completion(user)
})
}
}
}

我尝试了什么

如何修复 Swift 中的"线程 1：致命错误：解开可选值时意外发现 nil ">

https://learnappmaking.com/found-nil-while-unwrapping-optional-value/

我浏览并检查了这些网站，但它不起作用。 我认为用户信息无法成功取出。

补充资料

如果我们有其他缺失的信息，我们将添加其他信息。 由于我经常在 3 周内不了解 Swift，我希望您告诉我具体的代码等。 另外，如果您能告诉我错误的原因，我很高兴。

固件/刀具版本

Answer 1

您正在尝试从UserApi Singleton类访问CURRENT_USER_UID，该类是可选的计算属性，似乎返回nil。 如果当前没有用户登录，则 Firebase 身份验证将返回 nil 而不是 uid

Auth.auth().currentUser?.uid // Because of Optional Chaining  

我建议您安全地解开可选包。

func loadUser() {
UserApi.shared.observeUser { (user) in
self.isFollowing(userUid: user.uid!, completed: { (value) in
if let currentUser = UserApi.shared.CURRENT_USER_UID {
if user.uid != currentUser {
user.isFollowing = value
self.users.append(user)
self.tableView.reloadData()
}
} else {
// Current user not Signed-In
}
})
}
}