Question

我的核心数据项目中有2个VC。在VC1中，我有一个表视图，用于在我的coredata数据库中显示名称。在我的VC2中，我输入实体的详细信息。现在我想在用户选择特定行时更新我的数据库。当用户选择一行时，它将移动到VC2并在文本字段中显示名称，如果用户更新其中的任何内容，它将更新。我的代码如下。请建议我接下来要做什么。

输入详细信息 -

import UIKit
import CoreData

class EnterDetailViewController: UIViewController {

    @IBOutlet weak var nametextfield: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }



    @IBAction func savedata(sender: AnyObject)
    {
        let appdelegate = UIApplication.sharedApplication().delegate as! AppDelegate

        let managedcontext = appdelegate.managedObjectContext

        let entity = NSEntityDescription.entityForName("Person", inManagedObjectContext: managedcontext)

        let person = NSManagedObject(entity: entity!, insertIntoManagedObjectContext: managedcontext)
        person.setValue(self.nametextfield.text, forKey: "name")

        do
        {
            try managedcontext.save()
            print("SAVED")

        }
        catch let error as NSError
        {
            print("could not save \(error), \(error.userInfo)")
        }

        self.navigationController?.popToRootViewControllerAnimated(true)

    }




}

VC1-在表格视图中显示

import UIKit
import CoreData

class ViewController: UIViewController,UITableViewDataSource,UITableViewDelegate {

    @IBOutlet weak var tableview: UITableView!

    var people = [NSManagedObject]()

    let manai = UIApplication.sharedApplication().delegate as! AppDelegate
    //var person :NSMutableArray = []


    override func viewDidLoad() {
        super.viewDidLoad()
        tableview.delegate = self
        tableview.dataSource = self


        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    override func viewWillAppear(animated: Bool)
    {
           print("CALLING FETCHDATA")
        self.fetchData()
        print("RELOADING DATA")

        self.tableview.reloadData()
           }

func fetchData()
{
    let appdelegate = UIApplication.sharedApplication().delegate as! AppDelegate

    let managedContext = appdelegate.managedObjectContext

    let fetchRequest = NSFetchRequest(entityName: "Person")

    do
    {
        people = try managedContext.executeFetchRequest(fetchRequest) as! [NSManagedObject]
        print(people)
        print("FETCHING DATA")

    }
    catch let error as NSError
    {
        print("could not fetch \(error), \(error.userInfo)")
    }

    }


    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int
    {
        return people.count

    }


    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
    {
        let cell = self.tableview.dequeueReusableCellWithIdentifier("cellreuse", forIndexPath: indexPath) 


    let  person = people[indexPath.row]

        cell.textLabel?.text = person.valueForKey("name") as? String


        return cell

    }

    func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath)
    {
        let appdelegate = UIApplication.sharedApplication().delegate as! AppDelegate

        let managedContext = appdelegate.managedObjectContext

       if editingStyle == .Delete
       {
        managedContext.deleteObject(people[indexPath.row])
        }
      do
        {
            try managedContext.save()
            print("SAVED")

        }
        catch let error as NSError
        {
            print("could not save \(error), \(error.userInfo)")
        }


        }


        fetchData()

        self.tableview .reloadData()
        print("reload after delete")


    }


    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?)
    {
        if segue.identifier == "segueupdate"
        {



        }
    }


}

Answer 1

NSManagedObject的指定初始化程序是 initWithEntity:insertIntoManagedObjectContext:。您无法调用通用初始值设定项NSManagedObject()。

在您的情况下，您可以将managedobjectt声明为（隐式解包）可选

var managedobjectt = NSManagedObject!

为了确保在VC2中访问变量不会太快，您还可以将viewDidLoad()中的代码移至viewWillAppear()

在iOS9 swift中选择特定行时更新核心数据库

1 个答案: