将数据（标签）从TableViewCell传递到另一个ViewController

Question

I want to pass the Label from a TableViewCell to a ViewController when I click on the Cell. In the end it should be like twitter, that if you click on a cell with a Label you get passed on a detailViewController with the same Label init. My Code doesn't work as I just get the blanket Label from the Storyboard...

import UIKit
import Firebase

class JobTableViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {

@IBOutlet weak var tableView: UITableView!
var valueToPass:String!


 func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
    return true
}

 func numberOfSections(in tableView: UITableView) -> Int {
    return 1
}

 func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int{
    // Arvice return to count jobs
    return jobs.count
}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    print("You selected cell #\(indexPath.row)!")

    // Get Cell Label
    let indexPath = tableView.indexPathForSelectedRow!
    let currentCell = tableView.cellForRow(at: indexPath)! as UITableViewCell

    let valueToPass = currentCell.textLabel?.text
    print("value: \(valueToPass)")

    performSegue(withIdentifier: "toDetails", sender: valueToPass)
}

 func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell{
    let cell = tableView.dequeueReusableCell(withIdentifier: "JobCell", for: indexPath) as! JobTableViewCell
    let job = jobs[indexPath.row]
    cell.job = job

    //spacing
    cell.contentView.backgroundColor = UIColor.clear

    let whiteRoundedView : UIView = UIView(frame: CGRect(x: 10, y: 8, width: self.view.frame.size.width - 20, height: 120))

    whiteRoundedView.layer.backgroundColor = CGColor(colorSpace: CGColorSpaceCreateDeviceRGB(), components: [0.36, 0.39, 0.40, 1.0])
    whiteRoundedView.layer.masksToBounds = false
    whiteRoundedView.layer.cornerRadius = 2.0
    whiteRoundedView.layer.shadowOffset = CGSize(width: 0, height: 0)
    whiteRoundedView.layer.shadowOpacity = 0.0

    cell.contentView.addSubview(whiteRoundedView)
    cell.contentView.sendSubview(toBack: whiteRoundedView)

    cell.emojiLabel.text = cell.emojiString

    return cell
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "toDetails" {
        let destinationViewController = segue.destination as! JobDetailViewController
        destinationViewController.valueToPass = (sender as? String)!
    }
}

My Cell:

import UIKit
import Firebase

class JobTableViewCell: UITableViewCell {

@IBOutlet weak var jobLabel: UILabel!

var job: Job! {
    didSet {
        jobLabel.text = job.text
    }
}
}

Job.Swift:

import Foundation
import Firebase

class Job{

var text: String = ""
let ref: DatabaseReference!

init(text: String) {
    self.text = text
    ref = Database.database().reference().child("jobs").childByAutoId()
}

init(snapshot: DataSnapshot)
{
    ref = snapshot.ref
    if let value = snapshot.value as? [String : Any] {
        text = value["text"] as! String
    }
}

func save() {
    ref.setValue(toDictionary())
}

func toDictionary() -> [String : Any]
{
    return [
        "text" : text,
    ]
}
}

And in my DestinationController:

import UIKit
import Firebase

class JobDetailViewController: UIViewController {

 @IBOutlet weak var jobDetail: RoundText!



var valueToPass: String = ""

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    jobDetail.text = valueToPass
}

override func viewDidLoad() {
    super.viewDidLoad()

    title = "Jobinformation"
}
}

Answer 1

You should not be using cells to store data. You should have a data model that represents the data you are showing in the cells, and you should use the indexPath of the selected cell to look up the data in your data model.

Answer 2

Quick solution:

1. Change performSegue(withIdentifier: "yourSegueIdentifer", sender: self) to performSegue(withIdentifier: "yourSegueIdentifer", sender: valueToPass)

2.Your prepare for Segue method should looks like this:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
     if segue.identifier == "yourSegueIdentifer" {
         let destinationViewController = segue.destination as!   AnotherViewController
             destinationViewController.valueToPass = sender as? String
    }
}

3. On AnotherViewController create var valuteToPass: String = "" and set your label.text = valueToPass

But I think you should not use currentCell.textLabel.text value, instead use the original value. (like if you set your currentCell as cell.textLabel.cell = array[indexPath.row] , your valueToPass should be valueToPass = array[indexPath.row] )

EDIT:

You use didDeselectRowAt method, instead of didSelectRowAt.

Change func tableView(_ tableView: UITableView, didDeselectRowAt indexPath: IndexPath) to func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath)

Don't use global variable, create it in didSelectRowAt.

    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    print("You selected cell #\(indexPath.row)!")

    // Get Cell Label
    let indexPath = tableView.indexPathForSelectedRow!
    let currentCell = tableView.cellForRow(at: indexPath)! as UITableViewCell

    let valueToPass = currentCell.textLabel?.text
    print("value: \(valuteToPass)")

    performSegue(withIdentifier: "toDetails", sender: valueToPass)
}

On DestinationController:

class DestinationController: UIViewController {

var valuteToPass: String = ""

  override func viewDidLoad() {
    super.viewDidLoad()
   jobLabel.text = valueToPass
   }

}

EDIT2

JobTableViewController

1. delete var valueToPass:String!

Change let valueToPass = jobs[indexPath.row].text instead of let valueToPass = currentCell.textLabel?.text I checked this change in your code, this will work.

Answer 3

Hi I cant comment but im using @Dris answer and I kept getting this error that says

Could not cast value of type 'UITableViewCell' (0x115464e18) to 'NSString' (0x10fa594c8).

The SIGABRT targets the line destinationViewController.valueToPass = (sender as? String)!

Why is that?

this is basically my code

 func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        //  Determine what to do when a cell in a particular section is selected.
        print("did select:      \(indexPath.row)  ")

        // Get Cell Label
        let indexPath = tableView.indexPathForSelectedRow!
        let currentCell = tableView.cellForRow(at: indexPath)! as UITableViewCell

        valueToPass = currentCell.textLabel?.text
        print("valueToPass: \(String(describing: valueToPass))")
        performSegue(withIdentifier: "cellToView", sender: self)

    }

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        var cell:UITableViewCell?

        if tableView == self.tableView {

            let currentNotif = notificationList[indexPath.row]
            cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as UITableViewCell
            cell?.textLabel?.text = currentNotif.notifType
            cell?.detailTextLabel?.text = "\(currentNotif.notifTime) \n\(currentNotif.notifContent)"
        }

        if tableView == self.tableViewAnnounce {

            let currentAnnounce = announcementList[indexPath.row]
            cell = tableView.dequeueReusableCell(withIdentifier: "cellAnn", for: indexPath) as UITableViewCell
            cell?.textLabel?.text = currentAnnounce.annouceType
            cell?.detailTextLabel?.text = "\(currentAnnounce.annouceTime) \n\(currentAnnounce.annouceContent)"
        }

        return cell!

    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "cellToView" {
            // perform custom segue operation.

            let destinationViewController = segue.destination as! ExtendedAnnouncementViewController
            destinationViewController.valueToPass = (sender as? String)!
        }
    }

Answer 4

I'd avoid using a global variable to pass the data to the destination view controller. Defer the lookup until you are ready to pass the data.

And, avoid using force unwrap, it leads to runtime crashes.

Use something like this instead:

let segueIdentifier = "yourSegueIdentifer"
let labelDataSource: [String] = ["SomeText"]

func label(forIndexPath indexPath: IndexPath) -> String? {
    let index = indexPath.row
    guard labelDataSource.indices.contains(index) else { return nil }

    return labelDataSource[index]
}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    performSegue(withIdentifier: segueIdentifier, sender: indexPath)
}

func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    guard segue.identifier == segueIdentifier,
        let indexPath = sender as? IndexPath,
        let destinationViewController = segue.destination as? AnotherViewController else { return }

    destinationViewController.valuePassed = label(forIndexPath: indexPath)
}