Swift CoreData：显示特定数据的最佳方法？

Question

I did search and still can't figure out how to do this:

I have a tableViewVC which shows a list (cells) of data retrieved from a CoreData Entity: Person. The cell only shows the person name attribute of each data entry.

When I tap the cell (func didSelectRowAtIndexPath), it will go to the detailViewVC where I want to show the values of the rest of the attributes associated to that single data (ie age, gender, address, etc.).

I was originally thinking to pass the string value of the name from VC1 to VC2 and then do some sort of a loop in VC2 to search for the relevant data based on the name attribute, but if the names repeat in the database, this won't work. Definitely a stupid workaround which won't work.

So I am thinking to use a unique ID of each data entry, like ObjectID? If so, how to do? another better and more efficient way?

I am new so please be gentle and patient with me. Thanks!

EDIT:

VC1 has tableview:

import CoreData

class vc1: UIViewController, UITableViewDataSource, UITableViewDelegate {
    ... ... ...

    var personData = [Person]()

    override func viewDidAppear(animated: Bool) {
        fetchAndSetResults()
        medTableView.reloadData()
    }

    func fetchAndSetResults() {
        let app = UIApplication.sharedApplication().delegate as! AppDelegate
        let context = app.managedObjectContext
        let fetchRequest = NSFetchRequest(entityName: "Person")

        do {
            let results = try context.executeFetchRequest(fetchRequest)
            self.personData = results as! [Person]
        }

        catch let err as NSError {
            print(err.debugDescription)
        }
    }


    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        if let cell = tableView.dequeueReusableCellWithIdentifier("PersonCell") as? PersonCell {

            let person = personData[indexPath.row]

            cell.configureCell(person) //custom func that shows the string value of attribute "name" of entity "Person" on an IBOutlet label.

            return cell
        }

        else {
            return UITableViewCell()
        }
    }
    ... ...

    // Tapping a cell will present VC2_DetailView.
    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        let indexPath = tableView.indexPathForSelectedRow;
        let currentCell = tableView.cellForRowAtIndexPath(indexPath!) as! PersonCell

        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let vc = storyboard.instantiateViewControllerWithIdentifier("VC2_DetailView") as! VC2_DetailView

        // Pass person's name in the tapped cell to the label.text in VC2_DetailView.
        vc.receivedPersonName = currentCell.cellPersonName.text

        //vc.view.backgroundColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.6)
        //self.modalPresentationStyle = UIModalPresentationStyle.OverCurrentContext

        // Adding dispatch_async to eliminate double tapping on cell. VC2 will be presented.
        dispatch_async(dispatch_get_main_queue(), {
            self.presentViewController(vc, animated: true, completion: nil)
        })
    }
    ... ...

}

With this, VC2 will be presented when a cell is tapped. What I want to achieve is that VC2 will show other attributes associated to that specific person's name, such as "Age" and "Gender" of entity "Person" and show them in the relevant IBOutlet label in VC2.

More info: VC1 table has 3 cells: John, Jenny, and Josh. When I click Jenny, VC2 will present and her age and gender will be shown. Entity "Person" has 3 attributes: "name", "age" and "gender".

I am new so, any elaborate explanations are much appreciated!

Answer 1

您可以只传递实体本身。

Answer 2

OK, guys, no-one seemed to be interested in helping me deeper. I somehow resolved my problem this way:

  func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    //let indexPath = tableView.indexPathForSelectedRow;
    //let currentCell = tableView.cellForRowAtIndexPath(indexPath!) as! PersonCell

    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let vc = storyboard.instantiateViewControllerWithIdentifier("VC2_DetailView") as! VC2_DetailView

    // Pass person's name in the tapped cell to the label.text in VC2_DetailView.

    // Get all data stored in the coredata[indexpath] on the same tapped cell.
    let person = personData[indextPath.row]
    vc.receivedPersonName = person.name
    vc.receivedPersonAge = person.age
    vc.receivedPersonGender = person.sex

    //vc.view.backgroundColor = UIColor(red: 0, green: 0, blue: 0, alpha: 0.6)
    //self.modalPresentationStyle = UIModalPresentationStyle.OverCurrentContext

    // Adding dispatch_async to eliminate double tapping on cell. VC2 will be presented.
    dispatch_async(dispatch_get_main_queue(), {
        self.presentViewController(vc, animated: true, completion: nil)
    })
}

Basically, I retrieved all properties of a specific data and passed them to VC2.

My next challenge will be how to edit those data and save/update the existing data and avoid creating new or duplicating it.

Thanks all and happy coding!

Answer 3

Well, I actually simplified further my code, in order to show the details of the entity on a specific indexpath.row.

When the cell is clicked:

// Let's try a new method by passing indexpath.row interger.
    let index = indexPath.row
    VC2.receivedIndex = index

Therefore, VC2 will receive the index number of the tapped cell from VC1.

Then I implemented fetchAndResults() of the entity again in VC2 and simply using the received index number I was able to show all the details of that specific entity in relevant label.text(s).

For me, knowing the index number (before I asked you if there was a unique ObjectID, but I believe the index number is the unique ID) is better, so later I can implement the update function of the existing details.

Cheers!