CODEWITHSUNDEEP
swift
Peterses
Peterses

Reputation: 937

How to execute function after another?

I'm trying to execute loadQuestionToView() after executing loadQuestionsForTests() using defer, but I'm unsuccessful... Can you help me with that?

override func viewDidLoad() {
    super.viewDidLoad()
    
    defer {
        loadQuestionToView()
    }
    loadQuestionsForTest(testID: testID)
}

func loadQuestionToView() {
    questionLabel.text = self.questions[self.questionIterator].question
}

func loadQuestionsForTest(testID: String) {
    let docRef = db.collection(Constants.FStore.collectionTests).document(testID).collection("questions")

    docRef.getDocuments { (querySnapshot, error) in
        if let e = error {
            print(e)
        } else {
            if let snapshotDocuments = querySnapshot?.documents {
                for doc in snapshotDocuments {
                    let data = doc.data()
                    
                    let question: Question = Question(question: data["question"] as! String, correctAnswer: data["answerCorrect"] as! String, wrongAnswer1: data["answerWrong1"] as! String, wrongAnswer2: data["answerWrong2"] as! String, wrongAnswer3: data["answerWrong3"] as! String)

                    self.questions.append(question)
                    //print(self.questions[self.iterator].question)
                    
                }
            }
        }
    }
}

Upvotes: 0

Views: 80

Answers (2)

ANTRIKSH VERMA
ANTRIKSH VERMA

Reputation: 363

The best way to do is using closure. If you want learn about closures, here you go: https://docs.swift.org/swift-book/LanguageGuide/Closures.html

 override func viewDidLoad() {
    super.viewDidLoad()
    loadQuestionsForTest(testID: testID) { success in
        if success {
            questionLabel.text = self.questions[self.questionIterator].questio
        } else {
            // Whatever you want to do on failure
        }
    }
}

func loadQuestionsForTest(testID: String, @escaping completion: (Bool) -> Void)) {
    let docRef = db.collection(Constants.FStore.collectionTests).document(testID).collection("questions")

    docRef.getDocuments { (querySnapshot, error) in
        if let e = error {
            completion(false)
        } else {
            if let snapshotDocuments = querySnapshot?.documents {
                for doc in snapshotDocuments {
                    let data = doc.data()
                    
                    let question: Question = Question(question: data["question"] as! String, correctAnswer: data["answerCorrect"] as! String, wrongAnswer1: data["answerWrong1"] as! String, wrongAnswer2: data["answerWrong2"] as! String, wrongAnswer3: data["answerWrong3"] as! String)

                    self.questions.append(question)
                }
                completion(true)
            } else {
                completion(false)
            }
        }
    }
}

Upvotes: 1

Mohammad Eslami
Mohammad Eslami

Reputation: 544

override func viewDidLoad() {
    super.viewDidLoad()
    loadQuestionsForTest(testID: testID, completionHandler: { [weak self] result in
        // here I call loadQuestionToView when result is true
        if result {
            self?.loadQuestionToView()
        }
    })
}

func loadQuestionToView() {
    questionLabel.text = self.questions[self.questionIterator].question
}

func loadQuestionsForTest(testID: String, completionHandler: @escaping (Bool) -> Void) {
    let docRef = db.collection(Constants.FStore.collectionTests).document(testID).collection("questions")
    
    docRef.getDocuments { (querySnapshot, error) in
        if let e = error {
            print(e)
        } else {
            if let snapshotDocuments = querySnapshot?.documents {
                for doc in snapshotDocuments {
                    let data = doc.data()
                    
                    let question: Question = Question(question: data["question"] as! String, correctAnswer: data["answerCorrect"] as! String, wrongAnswer1: data["answerWrong1"] as! String, wrongAnswer2: data["answerWrong2"] as! String, wrongAnswer3: data["answerWrong3"] as! String)
                    
                    self.questions.append(question)
                    //print(self.questions[self.iterator].question)
                }
                completionHandler(true)
                return
            }
        }
        completionHandler(false)
    }
}

Upvotes: 0

Related Questions