Calling method from a specific childViewControllers class - ios

Question

Alright, hope I can explain this as clearly as possible.
I have a Parent ViewController which has a ContainerView, this will contain different viewControllers/Class. I'm changing the content of this container at runtime like this:
let newController = (storyboard?.instantiateViewController(withIdentifier: classIdentifierFromStoryboard))! as UIViewController
let oldController = childViewControllers.last! as UIViewController
oldController.willMove(toParentViewController: nil)
addChildViewController(newController)
newController.view.frame = oldController.view.frame
transition(from: oldController, to: newController, duration: 0, options: .transitionCrossDissolve, animations:{ () -> Void in
}, completion: { (finished) -> Void in
})
oldController.removeFromParentViewController()
newController.didMove(toParentViewController: self)
So for example, the current controller that shows on UI is firstVC, which kinda look like
class firstVC {
func removeAnnotations() {
//something that removes annotation from MapVC
}
}
On a certain event on the parent controller, how can I access the instance of firstVC so that i'll be able to call removeAnnotations? As of the moment I am getting nil, using this on parent controller firstVC.removeAnnotations, assumably this calls another instance of the class. Any help would be great! Hope my explanation makes sense. Thanks!

Answer 1

You could run down the child view controllers like this:
for case let vc as firstVC in self.childViewControllers {
vc.removeAnnotations()
}
This will run down all the child view controllers that are of type firstVC and execute the removeAnnotations method

Answer 2

in this code is child view controller ProfileViewController
in first create one object of child view controller like this
var objectProfile:ProfileViewController!
then viewDidLoad method
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
let storyboard = UIStoryboard(name: "Main", bundle: nil)
objectProfile = storyboard.instantiateViewController(withIdentifier: "ProfileViewController") as! ProfileViewController
objectProfile.view.frame = CGRect(x: -(self.view.frame.size.width - 40), y: 0, width: self.view.frame.size.width - 40, height: self.view.frame.size.height)
self.view.addSubview(objectProfile.view)
self.navigationController?.didMove(toParentViewController: objectProfile)
objectProfile.view.isHidden = true
}
then button click method code here
#IBAction func btnProfilePressed(_ sender: UIButton) {
UIView.animate(withDuration: 0.3) {
self.objectProfile.view.frame = CGRect(x: 0, y: 0, width: self.view.frame.size.width - 40, height: self.view.frame.size.height)
}
}
then touchesBegan
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
objectProfile.view.isHidden = false
UIView.animate(withDuration: 0.3) {
self.objectProfile.view.frame = CGRect(x: -(self.view.frame.size.width - 40), y: 0, width: self.view.frame.size.width - 40, height: self.view.frame.size.height)
}
}
complete set this code out put is