Container view function not calling in parent view - ios

Question

I'm trying to run a function in a container view that I added in the storyboard editor but when I call it in the parent view controller, nothing happens. I want to be able to call a function and change a property of the child view controller triggered from the parent. Am I doing something wrong or should I just be doing this another way?
TLDR: Trigger a function in a child view controller from parent
Parent View Controller:
// ViewController.swift
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var routeConfirmationView: UIView! //This is the container view that I'm trying to work with
var RouteSelectionViewController: RouteSelectionViewController?
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(routeConfirmationView)
self?.RouteSelectionViewController?.getRidOfLoadingCover(isHidden: true) //The code that isn't doing anything
}
}
Container View Controller:
import UIKit
class RouteSelectionViewController: UIViewController {
#IBOutlet weak var loadingCoverView: UIActivityIndicatorView!
override func viewDidLoad() {
super.viewDidLoad(
}
//The function that I want to trigger from the other view controller:
func getRidOfLoadingCover (isHidden: Bool){
if (isHidden == true) {
loadingCoverView.alpha = 0
}
else if (isHidden == false) {
loadingCoverView.alpha = 100
}
}
}
Storyboard:

Answer 1

To call functions, or access properties, in a View Controller embedded in a Container View, you need to get and keep a reference to that controller.
When the Container View loads the embedded VC, it calls Prepare For Segue. Grab your reference there:
class WithContainerViewController: UIViewController {
var routeSelectionVC: RouteSelectionViewController?
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let vc = segue.destination as? RouteSelectionViewController {
// save reference to VC embedded in Container View
self.routeSelectionVC = vc
}
}
#IBAction func didTap(_ sender: Any) {
if let vc = routeSelectionVC {
vc.getRidOfLoadingCover(isHidden: true)
}
}
}
class RouteSelectionViewController: UIViewController {
#IBOutlet weak var loadingCoverView: UIActivityIndicatorView!
override func viewDidLoad() {
super.viewDidLoad()
}
//The function that I want to trigger from the other view controller:
func getRidOfLoadingCover (isHidden: Bool){
if (isHidden == true) {
loadingCoverView.alpha = 0
}
else if (isHidden == false) {
loadingCoverView.alpha = 100
}
}
}
You will likely next ask about calling a function in the "parent" VC from the embedded VC. This can be done with protocol / delegate pattern, or with closures. Again, you can set that up in prepare for segue:
class WithContainerViewController: UIViewController {
var routeSelectionVC: RouteSelectionViewController?
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if let vc = segue.destination as? RouteSelectionViewController {
// set the closure in the VC embedded in Container View
vc.callbackClosure = {
self.routeSelectionButtonTapped()
}
// save reference to VC embedded in Container View
self.routeSelectionVC = vc
}
}
#IBAction func didTap(_ sender: Any) {
if let vc = routeSelectionVC {
vc.getRidOfLoadingCover(isHidden: true)
}
}
func routeSelectionButtonTapped() -> Void {
print("Button in RouteSelectionViewController in Container View was tapped!")
}
}
class RouteSelectionViewController: UIViewController {
#IBOutlet weak var loadingCoverView: UIActivityIndicatorView!
var callbackClosure: (() -> ())?
override func viewDidLoad() {
super.viewDidLoad()
}
//The function that I want to trigger from the other view controller:
func getRidOfLoadingCover (isHidden: Bool){
if (isHidden == true) {
loadingCoverView.alpha = 0
}
else if (isHidden == false) {
loadingCoverView.alpha = 100
}
}
#IBAction func didTap(_ sender: Any) {
callbackClosure?()
}
}

Answer 2

I guess you did not set the RouteSelectionViewController variable (btw., variable names should start with a small letter), so it is nil and nothing happens.
If you want you embed a view controller into another, you need to implement the view controller containment requirements (see documentation).