One delegate Two classes - ios

Question

I am using a UISearchController with GoogleMap Autocomplete View controller to send data to my view controllers.
I have a Tabbar controller and I want to send the data two my ViewController A and B.
I have done all the necessary jobs but only one ViewController gets notified when user has used the UISearchController.
I have tried setting the delegate of each tab to nil when I move to the other tab, For example if I move from ViewController A to B
I will set the delegate of A to nil and then set the delegate of B to itself.
I am kinda new to swift so Can anyone help me understand why isn't this working?
I have tried debugging my code to see is my delegate is nil and it wasn't .
Here is how i set and unset the delegate
func setDelegate() {
print("MapViewController is not nil")
print(resultsViewController?.delegate)
resultsViewController?.delegate = self
print(resultsViewController?.delegate)
}
func unSetDelegate() {
print("MapViewController is nil")
resultsViewController?.delegate = nil
}

Answer 1

You need an observer pattern, if you need that one class instance notify to a number of other instances you need make an array of delegates (called observers) and register and deregister from that notifier instance class
Further info Wikipedia Observer Pattern
example code
This is the protocol that must implement any observer class
protocol GeotificationsManagerObserver : NSObjectProtocol{
func nearestGeotificationsHasChanged(pgeotifications:[Geotification])
}
Notifier class
class GeotificationsManager: NSObject {
/**...*//code
fileprivate var observers : [GeotificationsManagerObserver] = []
/**...*//code
}
Observers methods
extension GeotificationsManager
{
func addGeotificationsManagerObserver(observer:GeotificationsManagerObserver)
{
for currentObs in self.observers {
if(observer.isEqual(currentObs))
{
//we don't want add again
return
}
}
self.observers.append(observer)
}
func removeGeotificationsManagerObserver(observer:GeotificationsManagerObserver)
{
var observerIndex = -1
for (index,currObserver) in self.observers.enumerated() {
if(observer.isEqual(currObserver))
{
observerIndex = index
break
}
}
if(observerIndex != -1)
{
self.observers.remove(at: observerIndex)
}
}
//here make the notification to all observers in observers array
func nearestsGeotificationsHasChanged()
{
for currObserver in self.observers {
currObserver.nearestGeotificationsHasChanged(pgeotifications: self.getNearesGeotifications())
}
}
}
Important
You must remove the observer once you don't need being notified if not you will have memory issue
Example: You can add a UIViewController as Observer in viewDidAppear and can be removed in viewDidDisappear