How to call protocol function correctly?

Question

So, I need to make notification handler class for each notification that my app received from the server. I make class like below for that purpose:

protocol NotificationHandlerDelegate: class {
    func receiveNotification(content: Any)
}

class NotificationHandler{

   var delegate : NotificationHandlerDelegate!

   func handleTransactionNotif(content: Any, rootVC: UIViewController){

       delegate?.receiveNotification(content: content)
       ((rootVC as! UINavigationController).viewControllers[0] as! UITabBarController).selectedIndex = 3

   }


}

And below is how I called it on my view controller:

class TransactionsViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, TransactionsCellDelegate, NotificationHandlerDelegate{

   override func viewWillAppear(_ animated: Bool) {
       let nh = NotificationHandler()
       nh.delegate = self

       self.navigationController?.navigationBar.isHidden = true
   }


   func receiveNotification(content: Any) {
       print("called: \(content)")
       let contentJSON = JSON(content)
       goToScreenAccording(to: "\(contentJSON["status"])", selectedData: content as! [String: Any])
   }

}

the problem is that receiveNotification not called whenever I receive notification. Am I doing something wrong?

Answer 1

Use NotificationHandler as singleton, so you can refer to the same instance:

class NotificationHandler {

   weak var delegate: NotificationHandlerDelegate?

   static let shared = NotificationHandler()

   private init(){}

   func handleTransactionNotif(content: Any, rootVC: UIViewController){

       delegate?.receiveNotification(content: content)
   ((rootVC as! UINavigationController).viewControllers[0] as! UITabBarController).selectedIndex = 3

   }
}

class TransactionsViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, TransactionsCellDelegate, NotificationHandlerDelegate{

   override func viewWillAppear(_ animated: Bool) {
       let nh = NotificationHandler.shared
       nh.delegate = self
       self.navigationController?.navigationBar.isHidden = true
   }
   //...
}

And remember to use NotificationHandler.shared in AppDelegate too.