Passing data between controllers using combine not working - swift

Question

I am starting on combine with swift, but having some hard time (had experience working in swiftui before).
So the question is how to perform certain operation:
lets say i have vc1. and I go to vc2 from there
2.then i start asynchronos network closure and come back to vc1 (by popping out vc2).
Now say i want to ge just a string from vc2's asycnrhoss clousre to vc1 when i am back to vc1.
how can i achieve this?
I want to use publisher of lets say <String, Never>
how can I subscribe in my vc1 and publish or send it from vc2 ?
I am using this approach but its not working, it never comes to code under sink.....
public class Parent {
public static let shared = Parent()
public var publisher = PassthroughSibject<String,Never>()
}
class vc1: ViewController {
func viewdidLoad() {
let subscription = Parent.shared.oublisehr.sink { (result) in
print(result)
}
}
func navigatetoVC1() {
///// some code to navigate to vc1
}
func button() {
self.navigatetoVC1
}
}
class vc2: ViewController {
func viewDidload() {
///
}
func performsomeOperation() {
someasyncoperation(completion: { result in
switch result {
case .success:
//send some data to vc1
Parent.shared.publisher.send("testdata")
case .failure:
//send some data to vc1
})
self.dismisVC2() //some method to pop out vc2
}
}

Answer 1

Your code is almost right, except you are using your Anycancellable inside viewdidload, so its scope is getting exhausted. So use it outside in the view controller as an optional AnyCancellable type.
Below code should work.
class vc1: ViewController {
var subscription = AnyCancellable?
func viewdidLoad() {
self.subscription = Parent.shared.oublisehr.sink { (result) in
print(result)
}
}
func navigatetoVC1() {
///// some code to navigate to vc1
}
func button() {
self.navigatetoVC1
}
}