swift - 类型 '[Users]'的值没有成员 'username'

Question

我正在尝试创建一个简单的用户登录ViewController，它连接到充满我的应用程序用户信息的数据库，但是出现标题中指出的错误。

import UIKit
import Alamofire

class Users: Decodable {
    let username: String
    let email: String
    let password: String

    init(username: String, email: String, password: String) {
        self.username = username
        self.email = email
        self.password = password
}


class LoginVC: UIViewController {

    var loggingin = [Users]()

    @IBOutlet weak var usernameTxtField: UITextField!

    @IBOutlet weak var passwordTxtField: UITextField!

    @IBOutlet weak var checkCredsBtn: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        let jsonURL = "http://host-2:8888/getLogin.php"
        let url = URL(string: jsonURL)

        URLSession.shared.dataTask(with: url!) { (data, response, error) in

            do {

                self.loggingin = try JSONDecoder().decode([Users].self, from: data!)

                for eachUser in self.loggingin {
                    print(eachUser.username + " : " + eachUser.password)
                }

            }
            catch {
                print("Error")
            }
        }.resume()

    }
    @IBAction func checkCreds(_ sender: Any) {
        if usernameTxtField == loggingin.username && passwordTxtField == loggingin.password {
            print("YES")
            }
        }
    }
}

Answer 1

编译时间错误的原因出现在checkCreds函数中，您试图直接从数组中访问username和password属性，这显然是不正确的。相反，您应该从loggingin数组中获取所需的对象，并对其属性进行比较:

@IBAction func checkCreds(_ sender: Any) {
    let currentUser = loggingin[0]

    if usernameTxtField == currentUser.username && passwordTxtField == currentUser.password {
        print("YES")
    }
}

在上面的示例中，我刚得到第一个对象；我假设您已经能够获取所需的对象currentUser(使用的索引)，以便从loggingin获取对象。