Swift Firebase 选择 UITableView 原型单元 - UI 问题答案

【问题标题】：Swift Firebase Selected UITableView Prototype Cells - UI ProblemSwift Firebase 选择 UITableView 原型单元 - UI 问题
【发布时间】：2020-12-31 16:38:32
【问题描述】：

有些用户正在从 firebase 下载并显示在 UITableView 上，其中的单元格是可选择的，一旦被选中，就会有一个复选标记。所以从firebase是异步下载的，所以我认为这可能是我解决问题的开始，但不确定。选择时，当查看视图时，允许说两个单元格，然后开始滚动列表时，将在用户未选择它们时选择其他单元格。下面将是发生的代码和图片。

Firebase 调用

func getTableViewData() {
    Database.database().reference().child("Businesses").queryOrdered(byChild: "businessName").observe(.childAdded, with: { (snapshot) in
        let key = snapshot.key
        
        if(key == self.loggedInUser?.uid) {
            print("Same as logged in user, so don't show!")
        } else {
            if let locationValue = snapshot.value as? [String: AnyObject] {
                let lat = Double(locationValue["businessLatitude"] as! String)
                let long = Double(locationValue["businessLongitude"] as! String)
                let businessLocation = CLLocation(latitude: lat!, longitude: long!)
                
                let latitude = self.locationManager.location?.coordinate.latitude
                let longitude = self.locationManager.location?.coordinate.longitude
                let userLocation = CLLocation(latitude: latitude!, longitude: longitude!)
                
                let distanceInMeters: Double = userLocation.distance(from: businessLocation)
                let distanceInMiles: Double = distanceInMeters * 0.00062137
                let distanceLabelText = String(format: "%.2f miles away", distanceInMiles)
                
                var singleChildDictionary = locationValue
                singleChildDictionary["distanceLabelText"] = distanceLabelText as AnyObject
                singleChildDictionary["distanceInMiles"] = distanceInMiles as AnyObject
                self.usersArray.append(singleChildDictionary as NSDictionary)
                self.usersArray = self.usersArray.sorted {
                    !($0?["distanceInMiles"] as! Double > $1?["distanceInMiles"] as! Double)
                }
            }
            //insert the rows
            //self.followUsersTableView.insertRows(at: [IndexPath(row:self.usersArray.count-1,section:0)], with: UITableViewRowAnimation.automatic)
            self.listedBusiness.reloadData()
        }
    }) { (error) in
        print(error.localizedDescription)
    }
    
}

表格视图设置

// MARK: - Table view data source

override func numberOfSections(in tableView: UITableView) -> Int {
    return 1
}

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    
    if searchController.isActive && searchController.searchBar.text != ""{
        return filteredUsers.count
    }
    return self.usersArray.count
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! CustomerAddSelectedBusinessesCell
    
    var user : NSDictionary?
    
    if searchController.isActive && searchController.searchBar.text != ""{
        
        user = filteredUsers[indexPath.row]
    } else {
        user = self.usersArray[indexPath.row]
    }
    
    if cell.isSelected == true {
        
        var user = self.usersArray[indexPath.row]
        
        if CLLocationManager.locationServicesEnabled() {
            switch(CLLocationManager.authorizationStatus()) {
            case .notDetermined, .restricted, .denied:
                print("No access")
                cell.businessName.text = String(user?["businessName"] as! String)
                cell.businessStreet.text = String(user?["businessStreet"] as! String)
                cell.businessCity.text = String(user?["businessCity"] as! String)
                //cell.selectedCell.image = UIImage(named: "cellSelected")
                
                let businessProfilePicture = String(user?["profPicString"] as! String)
                if (businessProfilePicture.count) > 0 {
                    let url = URL(string: (businessProfilePicture))
                    DispatchQueue.global().async {
                        let data = try? Data(contentsOf: url!)
                        DispatchQueue.main.async {
                            let image = UIImage(data: data!)?.potter_circle
                            cell.businessImage.contentMode = UIView.ContentMode.scaleAspectFill
                            cell.businessImage.image = image
                        }
                    }
                } else {
                    let image = UIImage(named: "default")?.potter_circle
                    cell.businessImage.contentMode = UIView.ContentMode.scaleAspectFill
                    cell.businessImage.image = image
                }
                
                //cell.profileImage.image =
            //cell.businessDistance.text = String(user?["distanceLabelText"] as! String)
            case .authorizedAlways, .authorizedWhenInUse:
                print("Access")
                print("****Called")
                cell.businessName.text = String(user?["businessName"] as! String)
                cell.businessStreet.text = String(user?["businessStreet"] as! String)
                cell.businessCity.text = String(user?["businessCity"] as! String)
                cell.businessDistance.text = String(user?["distanceLabelText"] as! String)
                //cell.selectedCell.image = UIImage(named: "cellSelected")
                
                let businessProfilePicture = String(user?["profPicString"] as! String)
                if (businessProfilePicture.count) > 0 {
                    let url = URL(string: (businessProfilePicture))
                    DispatchQueue.global().async {
                        let data = try? Data(contentsOf: url!)
                        DispatchQueue.main.async {
                            let image = UIImage(data: data!)?.potter_circle
                            cell.businessImage.contentMode = UIView.ContentMode.scaleAspectFill
                            cell.businessImage.image = image
                        }
                    }
                } else {
                    let image = UIImage(named: "default")?.potter_circle
                    cell.businessImage.contentMode = UIView.ContentMode.scaleAspectFill
                    cell.businessImage.image = image
                }
            }
        } else {
            print("Location services are not enabled")
        }
        
    } else if cell.isSelected == false {
        
        var user = self.usersArray[indexPath.row]
        
        if CLLocationManager.locationServicesEnabled() {
            switch(CLLocationManager.authorizationStatus()) {
            case .notDetermined, .restricted, .denied:
                print("No access")
                cell.businessName.text = String(user?["businessName"] as! String)
                cell.businessStreet.text = String(user?["businessStreet"] as! String)
                cell.businessCity.text = String(user?["businessCity"] as! String)
                //cell.selectedCell.image = UIImage(named: "cellNotSelected")
                
                let businessProfilePicture = String(user?["profPicString"] as! String)
                if (businessProfilePicture.count) > 0 {
                    let url = URL(string: (businessProfilePicture))
                    DispatchQueue.global().async {
                        let data = try? Data(contentsOf: url!)
                        DispatchQueue.main.async {
                            let image = UIImage(data: data!)?.potter_circle
                            cell.businessImage.contentMode = UIView.ContentMode.scaleAspectFill
                            cell.businessImage.image = image
                        }
                    }
                } else {
                    let image = UIImage(named: "default")?.potter_circle
                    cell.businessImage.contentMode = UIView.ContentMode.scaleAspectFill
                    cell.businessImage.image = image
                }
                
                //cell.profileImage.image =
            //cell.businessDistance.text = String(user?["distanceLabelText"] as! String)
            case .authorizedAlways, .authorizedWhenInUse:
                print("Access")
                print("%called")
                cell.businessName.text = String(user?["businessName"] as! String)
                cell.businessStreet.text = String(user?["businessStreet"] as! String)
                cell.businessCity.text = String(user?["businessCity"] as! String)
                cell.businessDistance.text = String(user?["distanceLabelText"] as! String)
                //cell.selectedCell.image = UIImage(named: "cellNotSelected")
                
                let businessProfilePicture = String(user?["profPicString"] as! String)
                if (businessProfilePicture.count) > 0 {
                    let url = URL(string: (businessProfilePicture))
                    DispatchQueue.global().async {
                        let data = try? Data(contentsOf: url!)
                        DispatchQueue.main.async {
                            let image = UIImage(data: data!)?.potter_circle
                            cell.businessImage.contentMode = UIView.ContentMode.scaleAspectFill
                            cell.businessImage.image = image
                        }
                    }
                } else {
                    let image = UIImage(named: "default")?.potter_circle
                    cell.businessImage.contentMode = UIView.ContentMode.scaleAspectFill
                    cell.businessImage.image = image
                }
            }
        } else {
            print("Location services are not enabled")
        }
    }
    return cell
}

override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    tableView.deselectRow(at: indexPath, animated: true)
    
    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! CustomerAddSelectedBusinessesCell
    
    let user = usersArray[indexPath.row]
    let name = user!["uid"] as? String
    var NSdata = NSDictionary()
    var realArray = [NSDictionary]()

    if let cell = tableView.cellForRow(at: indexPath as IndexPath) {
        if cell.accessoryType == .checkmark{
            cell.accessoryType = .none
            print("Deleted \(name!)")
            if let idx = data.index(of:name!) {
                data.remove(at: idx)
                print(data)
            }
        } else {
            cell.accessoryType = .checkmark
            data.append(name!)
            print(data)
        }
    }
    print(data)
}

视图加载后选定的单元格

看似已选中但未选中的单元格

【问题讨论】：

标签： ios swift firebase uitableview

【解决方案1】：

这是最常见的细胞可重复使用问题。当您滚动时，屏幕上可见的单元格将被重复使用。例如。您有 5 个可见的单元格。当您选择 2,3 并向下滚动时，将选择 7,8。为避免这种情况，您有 2 个选项。

您可以使用外部 Bool 数组来管理这个（Bool 数组计数必须与您的数组计数相同）。
您可以将 bool 变量放入您的用户字典中进行管理。

因此，每当您滚动时，不会自动选择新可见的单元格。

【讨论】：