swift - 更新 TableView 和核心数据

Question

我的核心数据中有一些数据，我将其显示在表格 View 上。我想在单击单元格时更新表格 View 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
}

但是我收到一些错误，例如:-

Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key starImage.'

Answer 1

请合并您的变量名称:循环中有两个不同的data变量，这会导致困惑和错误

更好

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

尽管如此，我建议使用更具体的类型并仅创建一次图像

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)
}