ios - 如何正确调用协议(protocol)函数？

Question

因此，我需要为我的应用从服务器收到的每个通知创建通知处理程序类。为此，我制作了如下类:

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

   }


}

下面是我在 View Controller 上调用它的方式:

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])
   }

}

问题是当我收到通知时，receiveNotification 没有被调用。难道我做错了什么？

Answer 1

将 NotificationHandler 用作单例，因此您可以引用相同的实例:

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
   }
   //...
}

并且记得在 AppDelegate 中也使用 NotificationHandler.shared。