如何在swift 3中使用单例类、数组存储和检索多个用户数据，即姓名、电子邮件和密码

class User {
    static let shared = User()
    
    var name: String?
    var email: String?
    var password: String?
    
    private init() {}
}

var users: [User] = []

let user1 = User.shared
user1.name = "John"
user1.email = "john@example.com"
user1.password = "password123"

users.append(user1)

let user2 = User.shared
user2.name = "Jane"
user2.email = "jane@example.com"
user2.password = "password456"

users.append(user2)

for user in users {
    if let name = user.name, let email = user.email, let password = user.password {
        print("Name: \(name), Email: \(email), Password: \(password)")
    }
}