Passing same variable to container view with different value

Question

I have one button on main viewController which has default value nil which is associated by dropDown pod. On same viewController there is also a container view.

During first time loading, I get the default value of a variable from shared preferences and pass that value to container view by performSegue.

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
   if(segue.identifier == "dataToContainerView"){
    DispatchQueue.main.async {

   var secondVC = segue.destination as! secondViewController //container viewController
        secondVC.variable = self.variable  
    }
  }
}

Now I need to pass the value of same variable again by selecting from dropdown button by user.

 dropDown.selectionAction = { [unowned self] (index, item) in
        self.button.setTitle(item, for: UIControlState())
        self.variable = item
        print(item)
        self.performSegue(withIdentifier: "dataToContainerView", sender: nil)
  //performing segue to resend the new value of the variable.
    }

The above code performs properly till print(item). But I am getting the following error on performSegue.

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'There are unexpected subviews in the container view. Perhaps the embed segue has already fired once or a subview was added programmatically?

How should I pass the value to container view second time overriding first value with the help of dropDown pod?

update:- I need the variable value so that I can pass it to json parser on container viewController. And the code on container viewController re-executes.

You can't do that, as the error says it. A solution is to set a custom closure or use a delegate. — Larme, Dec 19 '17 at 10:57
@DharmeshKheni please guide me through or help me with some code to figure out the solution — , Dec 19 '17 at 11:04
@Error Check this: https://stackoverflow.com/questions/24099230/delegates-in-swift — Dharmesh Kheni, Dec 19 '17 at 11:05

davidethell · Accepted Answer · 2017-12-19T13:04:10.860

1

You need to save a reference to your embedded controller so that you can update it again later. Do this in the first segue:

// Declare a local variable in your parent container:
var secondVC: secondViewController!

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if(segue.identifier == "dataToContainerView"){
        DispatchQueue.main.async {
            self.secondVC = segue.destination as! secondViewController 
            //container viewController
            self.secondVC.variable = self.variable  
        }
    }
}

Then later when you need to update the variable you can just reference it directly:

self.secondVC.variable = self.variable
self.secondVC.viewDidLoad()

edited Dec 19 '17 at 13:04

answered Dec 19 '17 at 10:57

davidethell

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I did this, but my container view doesn't get refreshed with the second value(The reason I am passing segue again). Actually I am passing this value in Json parser in container view. It doesn't executes the code on container viewController. Please check updated question sir. – Dec 19 '17 at 11:13
Do you have a function in the second view that you are calling to refresh the value? Please update your code to show the code in the secondVC that processes the JSON value. You have to be sure you are calling that function again each time you change the variable. – davidethell Dec 19 '17 at 11:19
Yes, there is function on container ViewController. It takes 4 variables, 3 from same viewController and 1 passed from the main viewController. When I perform segue it runs for first time. So if you can help me how to perform that function again after assigning value second time, will resolve my problem. – Dec 19 '17 at 11:32
Got the answer. I just needed to added `self.secondVC.viewDidLoad()`. If you can add this in your code above. I will mark it as answer. – Dec 19 '17 at 11:52
Ok I have updated my answer to show calling viewDidLoad() – davidethell Dec 19 '17 at 13:04

Passing same variable to container view with different value

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