Question

当我在dropDown中选择时如何添加项目，我可以显示类别列表并可以选择它，但如何将相关项目链接到父类并保存。

类别表：-

 import CoreData
extension Category {
    @nonobjc public class func fetchRequest() -> NSFetchRequest<Category> {
        return NSFetchRequest<Category>(entityName: "Category")
    }
    @NSManaged public var categoryColor: String?
    @NSManaged public var categoryName: String?
    @NSManaged public var items: NSSet?
}

物品类别：-

extension ItemForm {
    @nonobjc public class func fetchRequest() -> NSFetchRequest<ItemForm> {
        return NSFetchRequest<ItemForm>(entityName: "ItemForm")
    }
    @NSManaged public var itemName: String?
    @NSManaged public var price: Int64

    @NSManaged public var parent: Category?
}

在这里，当我选择类别时，我需要显示。

在此itemViewController中，如果我保存，则表示当我选择该类别按钮时应保存有关其父类的信息，而下拉菜单则应保存在该父类别中。

ItemViewController：-

 var buttonIndex : Int?

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        dropdownBtn.setTitle("\(arrCategory[indexPath.row].categoryName!)", for: .normal)
        animated(toogle: false)

        buttonIndex = indexPath.row

    }
      @IBAction func saveAction(_ sender: UIButton) {
        let selectedIndexInPopup = categoryType.title(for: .normal)

            itemSaveData()

            self.navigationController?.popViewController(animated: true)

    }
func itemSaveData(){

        guard let itemName = itemName.text else { return }
        guard let price = Int64(itemPrice.text!) else { return }

        guard let parentCategorty = buttonIndex else { return }

        let itemList = [
            "itemName": itemName,
            "price": price
            "parentCategory": parentCategorty

            ] as [String : Any]
         if isUpdate{
            editItemData(itemList: itemList, index: indexRow)
            isUpdate = false
        }else{
          saveItemData(itemList: itemList)
        }
}
    func saveItemData(itemList: [String:Any]){
               let item = NSEntityDescription.insertNewObject(forEntityName: "ItemForm", into: context) as! ItemForm
               item.itemName = itemList["itemName"] as! String
               item.price = itemList["price"] as! Int64
         item.parent = (itemList["parentCategory"] as? Category)
    do{
                   try context.save()
                print("Save Successfully")
               }catch let err{
                   print("college save error :- \(err.localizedDescription)")
               }
           }

    }

Answer 1

我认为您在问如何向现有的CategoryClass添加新的ItemClass对象。

首先，您应该使用primary keys来标识您的商品和类别

class CategoryClass: Object {
   @objc dynamic var category_id = NSUUID().uuidString
   @objc dynamic var categoryName : String = ""
   let items = List<ItemClass>()

    override static func primaryKey() -> String? {
        return "category_id"
    }
}

与ItemClass相同

class ItemClass: Object {
   @objc dynamic var item_id = NSUUID().uuidString
   @objc dynamic var itemName : String = ""
   @objc dynamic var price : Int64 = 0

   var parentCategory = LinkingObjects(fromType: CategoryClass.self, property: "items")
}

您似乎正在尝试保留类别的类变量

var categories = CategoryVaraible.categoryArray //not sure what this is

但不要那样做，

var categoryResults = Results<CategoryClass>? = nil

，并将categoryResults用作tableView的数据源。

当用户选择一个类别然后添加项目数据时，要保存它，您将基于在类别弹出窗口中选择的行获得该类别，然后创建一个项目，最后将其添加到写事务中：

func saveItemToCategory() {
   let category = self.categoryResults[selectedIndexInPopup]
   let item = ItemClass()
   item.itemName = some_item_name
   item.price = some_item_price

   try realm.write {
      category.items.append(item)
   }
}

如何使用coreData，swift将项目添加到其各自的父类别

1 个答案: