无法从完成处理程序取回数组

Posted 2023-02-23

【中文标题】无法从完成处理程序取回数组

【英文标题】：Can't get back the array from completion handler

【发布时间】：2020-05-12 01:12:36

【问题描述】：

我正在从 FireStore 读取数据并将其存储在我的数组中。我得到的数据在闭包内，所以我不得不使用 Completion Handler 将它传递到函数之外。但是当我调用完成处理函数时，我无法获取数组的值。它的所有打印都是[Project.CellComponents]。我知道肯定有一些愚蠢的错误，我很抱歉，因为我只是一个初学者。

OwnerHomeViewController：

class OwnerHomeViewController: UIViewController 

    @IBOutlet weak var tableView: UITableView!
    var listingDetailArray:[CellComponents] = []
    var docRef:DocumentReference!

    var typeOfListing:String = ""
    var charges:Int = 0
    var rating:Float = 0.0
    var nameOfListing:String = ""
    var cityName:String = ""
    var details:String = ""
    var currency:String = ""
    var days:String = ""

    override func viewDidLoad() 
        super.viewDidLoad()

        self.tableView.separatorStyle = UITableViewCell.SeparatorStyle.none

        getDataFromDB  (array) in
            print(array) ////Result in console '[Project.CellComponents]'
            listingDetailArray = array
        
    

    func getDataFromDB(completionHandler: @escaping(_ array: [CellComponents]) -> ()) 
        var tempArray:[CellComponents] = []

        docRef = Firestore.firestore().document("/Property/ktgEh96NXXTShCOBwj8QpEM79PB3/Hotel/2")
        docRef.getDocument  (docSnapshot, error) in
            if error != nil 
                return
            
            else 

                guard let docSnapshot = docSnapshot, docSnapshot.exists else  print("Error found");return 
                let myData = docSnapshot.data()
                print(myData?["Type"] as? String ?? "")
                self.typeOfListing = myData?["Type"] as? String ?? "Not Found"
                self.charges = Int(myData?["Charges"] as? String ?? "Not Found") ?? 0
                self.nameOfListing = myData?["Title"] as? String ?? "Not Found"
                self.currency = myData?["Currency"] as? String ?? "Not Found"
                self.days = myData?["Days"] as? String ?? "Not Found"
                self.details = myData?["Description"] as? String ?? "Not Found"

                let data2 = CellComponents(image: UIImage(named: "b")!, typeOfListing: self.typeOfListing , charges: self.charges, rating: 4.1, nameOfListing: self.nameOfListing , cityName: "Rawalpindi", detail: self.details, currency: self.currency, days: self.days)

                tempArray.append(data2)
                completionHandler(_:tempArray)
            
        
    


extension OwnerHomeViewController:UITableViewDataSource,UITableViewDelegate 

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int 
        return listingDetailArray.count
    

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell 
        let listingData = listingDetailArray[indexPath.row]
        let cell = tableView.dequeueReusableCell(withIdentifier: "OwnerHomeCell") as! OwnerHomeTableViewCell
        cell.setListingData(array: listingData)
        cell.details.isEditable = false
        return cell
    

还有我的 CellComponent 类

import Foundation
import UIKit

class CellComponents 

    var image: UIImage
    var typeOfListing:String
    var charges:Int
    var rating:Float
    var nameOfListing: String
    var cityName : String
    var detail : String
    var currency:String
    var days:String


    init (image:UIImage, typeOfListing:String, charges:Int, rating:Float, nameOfListing:String, cityName:String, detail:String, currency: String, days:String)
    
        self.image = image
        self.typeOfListing = typeOfListing
        self.charges = charges
        self.rating = rating
        self.nameOfListing = nameOfListing
        self.cityName = cityName
        self.detail = detail
        self.currency = currency
        self.days = days

    

【参考方案1】：

您的代码中有一些提前返回。您可以对其进行标记和调试。

【讨论】：

请准确回答！

if error != nil return and guard let else return 如果这里发生错误，它不会调用completionHandler

没有。我已经检查了那部分。那里没有错误。