How to get references for ViewController - ios

Question

Community!
I have a question regarding References in Swift 3 and Xcode.
My Plan is this:
At the moment my App has 4 Controllers. A MapViewController, a PositionController, a MarkerController and a APIDataController. Those of course handle the respective Models. My problem now comes in, when I want the controllers to communicate. Look at this code (Please ignore that most functions aren't implemented here):
First my MarkerController:
import Foundation
protocol MarkerControllerDelegate: class{
func willGetMarkerArray()
func didGetMarkerArray(_ newMarkerArray: Marker)
}
class MarkerController: NSObject{
var markerArray = [Marker]()
weak var delegate: MarkerControllerDelegate?
func createMarkerArray(){
}
func getMarkerArray() -> [Marker]{
return markerArray
}
}
extension MarkerController : APIDataControllerDelegate{
func didRetriveAPIData(_ APIDataModelArray: APIDataModel) {
createMarkerArray()
}
}
And now my APIDataController:
import Foundation
protocol APIDataControllerDelegate: class{
func didRetriveAPIData(_ APIDataModelArray: [APIDataModel])
}
class APIDataController: NSObject {
var APIDataModelArray = [APIDataModel]()
weak var delegate: APIDataControllerDelegate?
func retriveAPIData(){
//get the data
//.....
//finished getting data
delegate?.didRetriveAPIData(APIDataModelArray)
}
func getAPIDataModelArray() -> [APIDataModel] {
return APIDataModelArray
}
}
And finally the beginning of my MapViewController:
import UIKit
import GoogleMaps
import GoogleMaps
import CoreLocation
class MapViewController: UIViewController{
let positionController = PositionController()
let apiDataController = APIDataController()
let markerController = MarkerController()
override func viewDidLoad() {
super.viewDidLoad()
apiDataController.retriveAPIData()
//blablabla
}
//blablablabla
}
Now, this might be a lot of code at once, so let me explain you what is ought to happen:
At the beginning (or wherever in the code) MapViewController calls the retrieveAPIData method. Once the function is finished, APIDataController is planned to notify the MarkerController via the APIDataControllerDelegate-Protocol to start his work (run his createMarkerArray-Method).
Now, to do this, I have to declare a markerController-Instance as a Delegate to APIDataController. Now, since I have already created instances of all my controllers in mapViewController, I want to give those references to my other controllers where needed so that they all refer to the same Instances, kinda like a Singleton.
But, how do I create a Reference to my MapViewController IN my MapViewController, to pass it to my other Controllers so that they can from there go like:
let positionController = mapViewController.positionController?
Nothing I tried seem to work. So any help would be appreciated.
Also if there are better ways to let my Controllers communicate I am open to here them, I am sure there is a better way to do it than I currently try to do.

Answer 1

Using Delegates for the communication between the controllers is the recommended way to do it. Setting the delegates depends on the way these controllers interact in your app. Often you will have a segue from one app to another, that is a good chance to set delegates. You can also do it in code that is putting together your views