Question

我的核心数据中有一些数据，并在表格视图中显示。我想在单击单元格时更新tableview行。

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

            let cell = tableView.cellForRow(at: indexPath) as! ItemTableViewCell

            cell.starImage.image = UIImage(named: "Gray star icon")

            cell.selectionStyle = .none

            let context = coreData.persistentContainer.viewContext
            let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Item")

            do {
                let result = try context.fetch(request)
                let img = UIImage(named: "Gray star icon")
                for data in result as! [NSManagedObject] {

                    let data = img!.pngData() as NSData?

                    data?.setValue(data, forKey: "starImage")
                 }

            } catch {
                print("Failed")
            }

            coreData.saveContext()
            tableView.reloadData()
        }



func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    guard let cell = tableView.dequeueReusableCell(withIdentifier: "Cell") as? ItemTableViewCell else {
        return UITableViewCell()
    }

    cell.itemName.text = itemCategoryNameArray[indexPath.row]
    cell.itemDescription.text = itemDescriptionArray[indexPath.row]
    cell.itemCategory.text = itemCategoryTypeArray[indexPath.row]
    cell.starImage.image = UIImage(data: itemStarArray[indexPath.row])
    cell.profileImage.image = UIImage(data: itemImageArray[indexPath.row])
    return cell
}

但是我遇到了类似：-

的错误

由于未捕获的异常“ NSUnknownKeyException”而终止应用程序，原因：'[ setValue：forUndefinedKey：]：此类不是键值符合关键starImage的编码要求。'

Answer 1

请合并您的变量名：循环中有两个不同的data变量，这会引起混乱和错误

更好

for item in result as! [NSManagedObject] {
   let data = img!.pngData() as? NSData
   item.setValue(data, forKey: "starImage")
}

尽管如此，我还是建议使用更多特定类型的图像，并且仅创建一次图像

let request = NSFetchRequest<Item>(entityName: "Item")

do {
    let result = try context.fetch(request)
    let img = UIImage(named: "Gray star icon")
    let data = img!.pngData() as? NSData
    for item in result {
       item.starImage = data
    }
} catch {
    print("Failed", error)
}

Answer 2

尝试一下。在这里，我一次只添加了一次核心数据中的所有记录，然后在选择了Tableview单元之后，特定的选定数据将被更新并保存到核心数据中，并且单元图像还将进行门更新。

// GET DATA FROM CORE DATA...
func fetchData() {
        let context = coreData.persistentContainer.viewContext
        let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Item")

            do {
                let result = try context.fetch(request)
                managedObjects = result as! [NSManagedObject] //managedObjects             is a global array for the table content
                tableView!.reloadData()

            } catch {
                print("Failed")
            }

   }

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

            let cell = tableView.cellForRow(at: indexPath) as! ItemTableViewCell

            cell.starImage.image = UIImage(named: "Gray star icon")

            cell.selectionStyle = .none

            self.editData(with: self.managedObjects[indexPath.row], indexPath: indexPath)

    }

 func editData(with object: NSManagedObject, indexPath: IndexPath) {
        let img = UIImage(named: "Gray star icon")
        let data = img!.pngData() as NSData?
        (object as! Item).starImage = data
        coreData.saveContext()
        managedObjects[indexPath.row] = object
    }

更新tableview和coredata

2 个答案: