从Firebase检索Swift 3中的多个按钮 [英] Retrieve from firebase to multiple buttons in swift 3
问题描述
我正在尝试从Firebase检索数据并显示为多个按钮和标签. 检索后，我将其保存到字典中. 这是我的模特
I am trying to retrieve data from firebase and display into multiple buttons and label. After retrieving i am saving it into a dictionary. This is my model
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，但返回的却是 nil .我认为是异步firebase的原因.
I tried some ways but it return me nil .I think coz of asynchronous firebase.
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)
}
}
我仍在学习我的代码.我不知道从这里将数据显示为多个按钮并确定哪个按钮被单击"是正确答案.
Pls bare with my code i am still learning. I don't have any idea where to go from here in displaying my data into multiple buttons and identifying which button is 'clicked' is the CorrectAnwer.
如果您愿意的话，可以将我的代码重构为更简洁的方式，我将非常高兴.谢谢:)
推荐答案
尝试一下...
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
}
}
更新 我添加了一些扩展，这些扩展使您可以调整数组中元素的顺序，以便可以随机"设置答案标签，而正确的答案将永远不会在同一位置.扩展名来自此问题
update I've added extensions that allow you to shuffle the order of elements in an array so that you can set the answer labels "randomly" and the correct answer won't always be in the same place. The extension are courtesy of @NateCook from this question here
要知道是否选择了正确答案，只需检查所选按钮的文本是否为问题的正确答案属性的==，例如if buttonA.title(for: .normal)! == questions[0].correctAnswer {print("correct answer selected)"}.只需确保解开buttonA.title(for: .normal)的可选值，否则它前面将带有"optional"一词，因此将不完全等于正确的答案文本
To know if the correct answer was selected just check if the text of the selected button is == to the correctAnswer property of the question, for example if buttonA.title(for: .normal)! == questions[0].correctAnswer {print("correct answer selected)"} . Just make sure to unwrap the optional value of buttonA.title(for: .normal) otherwise it will have the word "optional" before it and therefore won't be exactly equal to the correct answer text
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