Passing values from one view controller to another in Swift

Question

I am working on Swift, I've got an error in tableview's didSelectRowAtIndexPath method. I want to pass a value to another view controller i.e 'secondViewController'. Here EmployeesId is an Array. The relevant code is as follows:

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    var view: Dashboard = self.storyboard?.instantiateViewControllerWithIdentifier("Dashboard") as Dashboard

    self.navigationController?.pushViewController(view, animated: true)
    secondViewController.UserId = employeesId[indexPath.item]  //getting an error here.
}

But I am getting this Error: fatal error: unexpectedly found nil while unwrapping an Optional value.

Any help will be appreciated.

what type is UserId? If it's a UILabel, then it'll be nil until the view is rendered. Also, where is secondViewController set? — Ron Fessler, Oct 31 '14 at 14:43
It should be indexPath.row, not indexPath.item, but I don't know if that will fix your problem. Are you sure that employeesId[indexPath.item] is not nil? — rdelmar, Oct 31 '14 at 14:58

score 8 · Accepted Answer · edited Jul 07 '21 at 10:33

Here's a general solution with two assumptions. First, UserId is not a UILabel. Second, you meant to use view which was instantiated in the second line, instead of using secondViewController

override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    var view: Dashboard = self.storyboard?.instantiateViewControllerWithIdentifier("Dashboard") as Dashboard
    view.userId = employeesId[indexPath.row]
    self.navigationController?.pushViewController(view, animated: true)
    
}

Here's what Dashboard looks like:

class Dashboard: UIViewController {
    var userId: String!
    @IBOutlet var userIDLabel: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        userIDLabel.text = UserId
    }

    ...
}

if i want to call a web service using "userid" in viewDidLoad() how i will call because user id return nil — Nandkishor mewara, Dec 08 '17 at 06:20

score 4 · Answer 2 · answered Jul 03 '17 at 10:53

We can pass value using "struct" in swift 3

Create a swift file in your project

Create a class in the swift file created like bellow

    class StructOperation {
      struct glovalVariable {
      static var userName = String();
     }
 }

Assing value to "static var userName" variable of " struct glovalVariable" in "StructOperation" class from First View Controller like

 @IBAction func btnSend(_ sender: Any) {
    StructOperation.glovalVariable.userName = "Enamul Haque";
   //Code Move to Sencon View Controller
 }

In destination view controller get value like bellow

 var username = StructOperation.glovalVariable.userName;

this is better way or passing global value as other controller?@Enamul Haque — Dhaval Bhadania, Jan 21 '18 at 08:05

score 0 · Answer 3 · answered Oct 31 '14 at 15:41

0

is UserId(strong, nonatomic) in the secondViewController?

If it is weak, it sent trash on the fly. You have to make it strong.

answered Oct 31 '14 at 15:41

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Passing values from one view controller to another in Swift

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