从CoreData删除字符串

Question

I'm having problems deleting an item from my Core Data, and having looked at lots of other examples and questions - they all say about deleting an NSManagedObject whereas I'm trying to delete the item at the indexPath.row (which is a String ).

var itemsArray = [String]()
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

What would I put in the following function?

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
    if (editingStyle == .delete) {

    }
}

Loading items in Core Data

func loadItems() {
    let request = NSFetchRequest<NSFetchRequestResult>(entityName: "Items")
    request.returnsObjectsAsFaults = false

    do {
        let results = try context.fetch(request)
        if results.count > 0 {
            for result in results as! [NSManagedObject] {
                if let product = result.value(forKey: "product") as? String {
                    self.itemsArray.append(product)
                }
            }
        }
    } catch {
        print("Error")
    }
}

Answer 1

To be able to delete the object you have to use the NSManagedObject as data source

var itemsArray = [Items]()

The loadItems can be reduced to

func loadItems() throws {
    let request = NSFetchRequest<Items>(entityName: "Items")
    request.returnsObjectsAsFaults = false
    itemsArray = try context.fetch(request)

}

Put the do - catch block around the loadItems() call and print the error instance, not a meaningless literal string.

In cellForRow use

let item = itemArray[indexPath.row]
let product = item.product

To delete the item you have to remove it from the data source, then delete the item in the context and then save the context:

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
    if editingStyle == .delete {
       let objectToDelete = itemArray[indexPath.row]
       itemArray.remove(at: indexPath.row)
       context.delete(objectToDelete)
       // here add code to save the context
       self.tableView.deleteRows(at: [indexPath], with: .fade) // and you have to update the table view
    }
}