在Swift中的视图控制器之间传递数据不起作用

Question

Would you please help me? The data (itemStr) is not passed even though the below code seems correct and I have already checked the similar questions on stack overflow.com:

1st view controller (BookTableViewController.swift):

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
      if let SecondController = segue.destination as? BookViewController {
            SecondController.itemStr = "43"        
        }        
}

2nd view controller (BookViewController.swift):

var itemStr = String()

override func viewDidLoad() {
        super.viewDidLoad()

        itemNoLabel?.text = "BNo:" + itemStr + " GYE"       
}

---

When I run the program, itemStr comes as nil. I do not get "43"?

Thanks, in advance, for your kind help. Guven

Answer 1

You're running into problems because you're not really presenting the UIViewController that you think you are. You're really presenting it's UINavigationViewController .

But you could still do something like this:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
      if let navigationViewController = segue.destination as? UINavigationController {

            guard let secondViewController = navigationViewController.topViewController as? BookViewController else { return }
            secondViewController.itemStr = "43"        
        }        
}