在fireift 3

Question

我正在尝试从firebase检索数据并显示到多个按钮和标签中。 检索后我将其保存到字典中。 这是我的模特

import Foundation
import Firebase

    class QuestionModel: NSObject {

        var CorrectAnswer: String!
        var Question: String!
        var optionA: String!
        var optionB: String!
        var optionC: String!

        init(snapshot: FIRDataSnapshot) {
            if let snapshotDict = snapshot.value as? Dictionary<String, Any> {
                CorrectAnswer = snapshotDict["CorrectAnswer"] as? String
                Question = snapshotDict["Question"] as? String
                optionA = snapshotDict["optionA"] as? String
                optionB = snapshotDict["optionB"] as? String
                optionC = snapshotDict["optionC"] as? String
            }
        }
    }

我的JSON

我尝试了一些方法，但它返回 nil 。我认为是异步firebase的。

这是我的代码。

import Foundation
import UIKit
import Firebase
import FirebaseDatabase

class AnsweringQuestionViewController: UIViewController {

    @IBOutlet weak var qLabel: UILabel!
    @IBOutlet weak var buttonA: UIButton!
    @IBOutlet weak var buttonB: UIButton!
    @IBOutlet weak var buttonC: UIButton!
    @IBOutlet weak var correctAnswer: UIButton!

    //var buttons: [UIButton]! thinking of using button tags?

    var ref: FIRDatabaseReference!
    var questionModel : [QuestionModel] = []

    override func viewDidLoad(){
        super.viewDidLoad()
      //  FIRDatabase.database().persistenceEnabled = true
        ref = FIRDatabase.database().reference()
        db()
    }
    func db(){
        ref.child("Science").observe(.value, with: {
            snapshot in
            for child in snapshot.children {
                let user = QuestionModel.init(snapshot: (child as? FIRDataSnapshot)!)
                self.questionModel.append(user)
            }
         self.qLabel.text = self.questionModel[0].Question
        self.buttonA.setTitle("\(self.questionModel[0].CorrectAnswer)", for: UIControlState.normal)
        }, withCancel: nil)
        }
}

请光着我的代码，我还在学习。我不知道从哪里开始将数据显示到多个按钮并确定哪个按钮被“点击”是CorrectAnwer。

如果您想以更清洁的方式重构我的代码，我将非常高兴。谢谢：）

Answer 1

试试这个......

import FirebaseDatabase

class Question {

   var correctAnswer: String?
   var question: String?
   var optionA: String?
   var optionB: String?
   var optionC: String?

   init(snapshot: FIRDataSnapshot){
       if let snap = snapshot.value as? [String: String] {
           correctAnswer = snap["CorrectAnswer"]
           question = snap["Question"]
           optionA = snap["OptionA"]
           optionB = snap["OptionB"]
           optionC = snap["OptionC"]
       }
   }

}




import FirebaseDatabase
import UIKit

class ViewController: UIViewController {

   @IBOutlet weak var qLabel: UILabel!
   @IBOutlet weak var buttonA: UIButton!
   @IBOutlet weak var buttonB: UIButton!
   @IBOutlet weak var buttonC: UIButton!
   @IBOutlet weak var correctAnswer: UIButton!

   var fireRootRef: FIRDatabaseReference!
   var questions = [Question]()

   override func viewDidLoad() {
       super.viewDidLoad()
       fireRootRef = FIRDatabase.database().reference()
       fetchQuestions(inCategory: "Science")
   }


   func fetchQuestions(inCategory category: String){
       let questionsRef = fireRootRef.child(category)

       questionsRef.observe(.value, with: {(snapshot)-> Void in

           var allQuestions = [Question]()
           for child in snapshot.children {
               allQuestions.append(Question(snapshot: child as! FIRDataSnapshot))
           }
           self.questions = allQuestions
           self.reloadUI(withQuestions: self.questions)
       })
   }

   func reloadUI(withQuestions questions: [Question]){
       guard questions.count > 0 else {return}

        if let answerToQuestion1 = questions[0].correctAnswer, let wrongAnswer = questions[0].optionA, let wrongAnswer2 = questions[0].optionB, let wrongAnswer3 = questions[0].optionC {

            let randomOrderedAnswers = [answerToQuestion1, wrongAnswer, wrongAnswer2, wrongAnswer3].shuffled()

            buttonA.setTitle(randomOrderedAnswers[0], for: .normal)
            buttonB.setTitle(randomOrderedAnswers[1], for: .normal)
            buttonC.setTitle(randomOrderedAnswers[2], for: .normal)
            correctAnswer.setTitle(randomOrderedAnswers[3], for: .normal)//keep in mind the correctAnswer label wont always contain the actual correct answer now

        } else {
            print("failed to get value for one of the answes options")
        }

       if let questionText = questions[0].question {
           qLabel.text = questionText
       } else {
           qLabel.text = "failed to get question text"
       }
   }

}




    extension MutableCollection where Indices.Iterator.Element == Index {
/// Shuffles the contents of this collection.
    mutating func shuffle() {
        let c = count
        guard c > 1 else { return }

        for (firstUnshuffled , unshuffledCount) in zip(indices, stride(from: c, to: 1, by: -1)) {
            let d: IndexDistance = numericCast(arc4random_uniform(numericCast(unshuffledCount)))
            guard d != 0 else { continue }
            let i = index(firstUnshuffled, offsetBy: d)
            swap(&self[firstUnshuffled], &self[i])
        }
    }
}

extension Sequence {
    /// Returns an array with the contents of this sequence, shuffled.
    func shuffled() -> [Iterator.Element] {
        var result = Array(self)
        result.shuffle()
        return result
    }
}

<强>更新 我添加了扩展程序，允许您对数组中元素的顺序进行随机排列，以便您可以随机设置答案标签＆＃34;并且正确的答案永远不会在同一个地方。延期礼貌来自this question here

的@NateCook

要知道是否选择了正确的答案，只需检查所选按钮的文本是否= =到问题的correctAnswer属性，例如if buttonA.title(for: .normal)! == questions[0].correctAnswer {print("correct answer selected)"}。只需确保打开buttonA.title(for: .normal)的可选值，否则它将包含单词＆＃34; optional＆＃34;在它之前，因此不会完全等于正确的答案文本