从 Firestore 读取数据时 Swift 出现索引超出范围错误

Question

我正在尝试从 Firestore 中提取图像数据并通过将图像添加到 tableView 单元格来更新 UI。

但是，我收到 Index out of Range 错误。我相信这是因为时间问题。

你能帮我解决这个问题吗？

提前致谢。

致命错误：索引超出范围：文件 Swift/ContiguousArrayBuffer.swift，第 444 行

    override func viewDidLoad() {
    super.viewDidLoad()
    
    createBubbleView()
    getDataFromFireStore()
    
    detailsTableView.delegate = self
    detailsTableView.dataSource = self

    // MARK: - NIB REGISTRATION
    detailsTableView.register(UINib(nibName: K.ingredientsNibName, bundle: nil), forCellReuseIdentifier: K.ingredientsCell)
    detailsTableView.register(UINib(nibName: K.stepsNibName, bundle: nil), forCellReuseIdentifier: K.stepsCell)
    detailsTableView.register(UINib(nibName: K.recipeNameNib, bundle: nil), forCellReuseIdentifier: K.recipeNameCell) }

    

  func getDataFromFireStore() {
    
    let db = Firestore.firestore()
for ingredient in ingredients {
        db.collection("Ingredients").whereField("name", isEqualTo: ingredient)
            .getDocuments() { [self] (querySnapshot, err) in
                if let err = err {
                    
                    print("Error getting documents: \(err)")
                } else {
                    for document in querySnapshot!.documents {
                        print(document.get("image")!)
                        if let imageURLsDB = document.get("image") as? [String] {

                            ingredientsImageURLs.append(document.get("image") as! String)
                            
                        }
                        
                        
                    }
            }
            }
    }
    

 // MARK: - RETURNS THE VALUE OF EACH CELL IN THE TABLEVIEW
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {


    let cell = detailsTableView.dequeueReusableCell(withIdentifier: K.ingredientsCell)
    switch indexPath.section {
    //        RECIPE NAME
    case 0:
        let cell = detailsTableView.dequeueReusableCell(withIdentifier: K.recipeNameCell) as! RecipeTitleCell
        cell.cookingTimeLabel.text = cookingTime
        cell.numberOfIngredientsLabel.text = String(ingredients.count)
        
        return cell
        
    //        INGREDIENTS
    case 1:
        let cell = detailsTableView.dequeueReusableCell(withIdentifier: K.ingredientsCell) as! IngredientsCell
        
        cell.ingredientName.text = ingredients[indexPath.row]
        
        cell.textLabel?.font = UIFont(name:"Mulish-regular", size:12)
        cell.textLabel?.numberOfLines = 0
        cell.textLabel?.lineBreakMode = NSLineBreakMode.byWordWrapping
        
        DispatchQueue.main.async {
            cell.ingredientImage.sd_setImage(with: URL(string: self.ingredientsImageURLs[indexPath.row]), placeholderImage: UIImage(systemName: "square.and.arrow.up"))
            self.detailsTableView.reloadData()
            
        }
        
        
        return cell

Answer 1

if let imageURLsDB = document.get("image") as? [String] {

   ingredientsImageURLs.append(document.get("image") as! String)
                        
}

您将 document.get("image") 检查为字符串数组，但是当您添加到数组时，您检查为字符串。

Answer 2

您正在为图像调用后端，然后重新加载数据，所以它每次都调用，设置图像不停。不能在 cellForRow 中调用 reload data，因为它会重复调用 table view delegates。

private func getImages()
        DispatchQueue.main.async {
        cell.ingredientImage.sd_setImage(with: URL(string:self.ingredientsImageURLs[indexPath.row]), placeholderImage: UIImage(systemName: "square.and.arrow.up"))
        self.imageArray = imagesFromFireStore
        self.detailsTableView.reloadData()
    }

//你可以把代码放在这里

if let imageURLsDB = document.get("image") as? [String] {
                        ingredientsImageURLs.append(document.get("image") as! String)
      //       here just append images to array and call
      self.reloadData()
  }

在表格视图中使用你的 imageArray[indexPath.row]

Answer 3

谢谢大家的意见。我就是这样解决的。

1. 在获得适量数据后将图像设置为单元格

   if ingredientsImageURLs.count ==  ingredients.count {
           cell.ingredientImage.sd_setImage(with: URL(string: self.ingredientsImageURLs[indexPath.row]), placeholderImage: UIImage(systemName: "square.and.arrow.up"))
       }
   

2. 下载完所有图片后重新加载数据。

   func getDataFromFireStore() {

   let db = Firestore.firestore()
   
   let recipeDocRef = db.collection("Recipes").document(selectedRecipeID).addSnapshotListener { [self] (snapshot, error) in
   
       if let titleDB = snapshot?.get("title") as? String {
           self.recipeTitle = titleDB
           titleLabel.text = recipeTitle
       }
   
       if let ingredientsDB = snapshot?.get("ingredients") as? [String] {
           self.ingredients = ingredientsDB
       }
   
       if let cookingTimeDB = snapshot?.get("cookingTime") as? String {
           self.cookingTime = cookingTimeDB
       }
   
       if let imageUrlDB = snapshot?.get("imageUrl") as? String {
           self.imageUrl = imageUrlDB
           recipeImageView.sd_setImage(with: URL(string: imageUrl), placeholderImage: UIImage(systemName: "square.and.arrow.up"))
   
       }
   
       if let cookingStepsDB = snapshot?.get("cookingSteps") as? [String] {
           self.steps = cookingStepsDB
       }
   
       if let stepImagesDB = snapshot?.get("stepImages")  as? [String]{
           self.stepsImages = stepImagesDB
       }
   
       for ingredient in self.ingredients {
           db.collection("Ingredients").whereField("name", isEqualTo: ingredient)
               .getDocuments()
               { [self] (querySnapshot, err) in
                   if let err = err {
   
                       print("Error getting documents: \(err)")
                   } else {
                       for document in querySnapshot!.documents {
                           ingredientsImageURLs.append(document.get("image") as! String)
                       }
                       self.detailsTableView.reloadData()
   
                   }
               }
           self.detailsTableView.reloadData()
       }
   
   }
   

   }