Passing same variable to container view with different value - ios

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.

Answer 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()