如何快速删除coredata数据库中的特定行数据

Posted 2023-03-04

【中文标题】如何快速删除coredata数据库中的特定行数据

【英文标题】：how to delete a particular row data in coredata database in swift

【发布时间】：2016-08-29 11:02:22

【问题描述】：

请帮帮我

这是我的代码

//

import UIKit
import CoreData


class SavedPageViewController: UIViewController, UITableViewDataSource, UITableViewDelegate , NSFetchedResultsControllerDelegate  


    @IBOutlet weak var tableView: UITableView!

    var tableTitleArray = [String]()
    var tableDetailArray = [String]()
    var tableTypeArray = [String]()
    var tableHoursArray = [String]()
    var tableImageArray = [NSData]()


    override func viewDidLoad() 
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    

    override func viewWillAppear(animated: Bool) 
// core data - show
         let appDel:AppDelegate = (UIApplication.sharedApplication().delegate as! AppDelegate)
         let context:NSManagedObjectContext = appDel.managedObjectContext

        var request = NSFetchRequest(entityName: "SavedIdea")
        request.returnsObjectsAsFaults = false;

        do 
            var result:NSArray = try context.executeFetchRequest(request)

            if (result.count > 0) 
                 self.tableTitleArray = result.valueForKey("heading") as! [String]
                 self.tableDetailArray = result.valueForKey("detail") as! [String]
                 self.tableTypeArray = result.valueForKey("type") as! [String]
                 self.tableHoursArray = result.valueForKey("time") as! [String]
                self.tableImageArray = result.valueForKey("image") as! [NSData]
            else
                print("0 result appear....error")
            tableView.reloadData()
        catch 
            let fetchError = ("returned error is \(error as! NSError)")
            print(fetchError)
        
    


    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int 

        return self.tableTitleArray.count
    


    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell 
        let cell = tableView.dequeueReusableCellWithIdentifier("Cell")! as! OTPTableViewCell

        cell.LabelTitle.text = tableTitleArray[indexPath.row]
        cell.LabelDetail.text = tableDetailArray[indexPath.row]
        cell.LabelType.text = tableTypeArray[indexPath.row]
        cell.LabelHours.text = String(tableHoursArray[indexPath.row])+"h"
        if tableImageArray[indexPath.row].length > 0            
            cell.ImgView.image =  UIImage(data: tableImageArray[indexPath.row])
        else
            cell.imageWidthConstraints.constant = 0
        

        return cell
    


    func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) 

    if editingStyle == .Delete 

        let appDel:AppDelegate = (UIApplication.sharedApplication().delegate as! AppDelegate)
        let context:NSManagedObjectContext = appDel.managedObjectContext


   /*     let deleterequest = NSFetchRequest(entityName: "SavedIdea")
        deleterequest.returnsObjectsAsFaults = false

        do 
            let savedData = try context.executeFetchRequest(deleterequest)

            if savedData.count > 0 

                for result: AnyObject in savedData
                    context.deleteObject(result.valueForKey("heading"))
                    print("NSManagedObject has been Deleted")
                
                try context.save()   catch 



     
    

我想从 tableview 中删除一个完整的行，即标题、详细信息、类型等。我的实体名称是 SavedData。我尝试了一些教程，但它们并没有满足我的需求。当我们向右滑动然后删除出现但不工作，因为我不知道代码。

【问题讨论】：

您正在删除实体本身而不是特定行，获取该特定行并执行删除操作并重新加载 tableview

查看***.com/questions/26047013/…

如果它解决了您的问题，请标记为正确答案

使用你奇怪的代码，这样做非常复杂（而且效率低下）。首先，您必须搜索并获取 NSManagedObject，因为您丢弃了引用，然后您必须删除代表数据源的 all 数组中行索引处的项目，然后您必须删除 @ Core Data 中的 987654324@，最后在 tableView 中调用 deleteRowsAtIndexPaths。

【参考方案1】：

通过这种方式，您可以根据实体从 coredata 中删除数据：这是从 coredata 中删除用户实体数据的简单函数：希望对您有所帮助 //从核心数据中删除信息

func deleteUserInfo()      
    let context = appdelegate.managedObjectContext
    let coord   = appdelegate.persistentStoreCoordinator

    let fetchRequest = NSFetchRequest(entityName: "entityname")
    //Here is the field on which u need to chk which record u want to delete just pass here in value ( acutal value) unique key = field in coredata 
    let predicate = NSPredicate(format: "uniqueKey == %@", "value")
    fetchRequest.predicate = predicate
    if #available(ios 9.0, *) 
       //You can put condition to delete data accordingly
        let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)

        do 
            try coord.executeRequest(deleteRequest, withContext: context)
        

        catch let error as NSError 
            //Error handling
        

        catch 

     else 

        // Fallback on earlier versions
        do 

           let users: NSArray = try appdelegate.managedObjectContext.executeFetchRequest(fetchRequest)

        //You can put condition to delete data accordingly
        for user in users 
            appdelegate.managedObjectContext.delete(user)
        

        try appdelegate.managedObjectContext.save()

         catch let error as NSError 
            //Error handling
        

        catch 
    

【讨论】：

我想从表视图中删除选定的行，所以我把这段代码放在 - func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) ...... ........当我像这样将 indexpath.row 放在用户上时，它在这一行显示错误 ..appDel.managedObjectContext.delete(user(indexPath.row))

chck 参数 u 传递整数？

我正在使用此代码在视图控制器中显示我的数据 -

chck 更新了答案，相应地更改了代码，在 coredata 中你需要使用 Predicate 来获取结果，然后你可以根据你的要求删除只是传递值和字段

【参考方案2】：

我希望这对于使用核心数据中的索引位置删除特定行很有用

func tableView(_ tableView: UITableView, commit editingStyle: 

UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) 


    let appDelegate = UIApplication.shared.delegate as! AppDelegate

    let context = appDelegate.persistentContainer.viewContext

    let requestDel = NSFetchRequest<NSFetchRequestResult>(entityName: "Contacts")
    requestDel.returnsObjectsAsFaults = false

    do 

        let arrUsrObj = try context.fetch(requestDel)

        let objectUpdate = arrUsrObj as! [NSManagedObject]

            context.delete(objectUpdate[indexPath.row]) // Deleting Object

     catch 
        print("Failed")
    

    // Saving the Delete operation
    do 
        try context.save()
        print("deleted")
        fetch()


     catch 
        print("Failed saving")