Question

所以，我正在努力学习如何正确处理CoreData。

这是我的代码：

import UIKit
import CoreData

class IngredientsViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, NSFetchedResultsControllerDelegate {

    let moc = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
    var fetchedResultsController: NSFetchedResultsController?


    override func viewDidLoad() {
        super.viewDidLoad()

        fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchIngredients(), managedObjectContext: moc!, sectionNameKeyPath: nil, cacheName: nil)
        fetchedResultsController?.delegate = self
        fetchedResultsController?.performFetch(nil)

    }

    func fetchIngredients() -> NSFetchRequest {

        var fetchRequest = NSFetchRequest(entityName: "DetailsForRecipe")
        let sortDescriptor = NSSortDescriptor(key: "ingredients", ascending: true)

        fetchRequest.predicate = nil
        fetchRequest.sortDescriptors = [sortDescriptor]
        fetchRequest.fetchBatchSize = 20

        return fetchRequest

    }

    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return fetchedResultsController?.sections?[section].numberOfObjects ?? 0
    }

    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCellWithIdentifier("ingCell", forIndexPath: indexPath) as! UITableViewCell
        if let ingCell = fetchedResultsController?.objectAtIndexPath(indexPath) as? DetailsForRecipe {
            cell.textLabel?.text = ingCell.ingredients
        }
        return cell
    }
}

和

import UIKit
import CoreData

class SingleIngredientViewController: UIViewController {

    @IBOutlet var ingField: UITextField!
    var moc = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    @IBAction func addIng(sender: AnyObject) {

        let entityDescription = NSEntityDescription.entityForName("DetailsForRecipe", inManagedObjectContext: moc!)
        let details = DetailsForRecipe(entity: entityDescription!, insertIntoManagedObjectContext: moc)
        details.ingredients = ingField.text

        var error: NSError?
        moc?.save(&error)

        if let err = error {
            var status = err.localizedFailureReason
            println(status)
        } else {
            println("Ingredient \(ingField.text) saved successfully!")
        }

        if let navigation = navigationController {
            navigation.popViewControllerAnimated(true)
        }
    }
}

我的模特：

import Foundation
import CoreData

    class DetailsForRecipe: NSManagedObject {

        @NSManaged var name: String
        @NSManaged var ingredients: String
        @NSManaged var image: NSData

    }

应用程序应在文本字段中插入成分名称，将其保存到coreData中，然后应在表格视图中检索它。当我给成分名称发短信并按＆＃34;添加＆＃34;时，prinln消息显示已成功保存，但表格视图不会更新。

我在这里做错了什么？我不是开发人员，我已经阅读了很多有关如何执行此操作的教程，但这非常令人困惑！所以原谅我这个。提前谢谢！

Answer 1

我还没有阅读完整的源代码，但通过立即看一眼，我没有看到你调用了tableview的reloadData函数。如果您没有为表格视图设置IBOutlet，则需要执行此操作，然后在其上调用reloadData()。

Answer 2

完成更改后，在表格视图上调用reloadData()。

CoreData - TableView没有更新

2 个答案: