為什么我的 Swift iOS 應用程序沒有收到我發布的通知

Question

我的應用程序中有三個自定義 swift 類。 一個是NetworkServices class，另外兩個是自定義的UIViewController類。 NetworkServices class 在打開 wifi 且有網絡連接時以及在關閉 wifi 且沒有網絡連接時向其他兩個類發送通知。 目前，應用程序開始發布isConnected通知並且代碼按預期執行。 然后我關閉 wifi 並發布isDisconnected並且代碼按預期執行。 但是，當我再次打開 wifi 時，已發送isConnected帖子，但兩個自定義UIViewController類中的任何一個都沒有收到它。 我的問題是為什么不呢？

這是我的NetworkServices class 中的相關代碼行；

protocol NetworkServicesDelegate: AnyObject {
    func sendStockInfo(stocksInfo: [String: StockInfo])
}

final class NetworkServices {
    
    static let sharedInstance = NetworkServices()

...

    public func startMonitoring() {
        monitor.start(queue: queue)
        
        self.monitor.pathUpdateHandler = { [weak self] path in
            if path.status == .satisfied {
                // connect the socket
                self?.socket.connect()
                print("DEBUG: self?.socket.connect() called")
            } else {
                // disconnect the socket
                self?.socket.disconnect()
//                print("DEBUG: self?.socket.disconnect() called")
                self?.isConnected = false
                // post notification that socket is now disconnected
                DispatchQueue.main.async {
                    print("DEBUG: Notification.Name(rawValue) called")
                    let name = Notification.Name(rawValue: isDisconnectedNotificationKey)
                    NotificationCenter.default.post(name: name, object: nil)
                }
            }
        }
    }
...
    
}

extension NetworkServices: WebSocketDelegate {
    
    func didReceive(event: WebSocketEvent, client: WebSocket) {
        
        switch event {
        case .connected(_):
            self.isConnected = true
            // post notification that socket is now connected
            let name = Notification.Name(rawValue: isConnectedNotificationKey)
            NotificationCenter.default.post(name: name, object: nil)
            print("DEBUG: Notification isConnected posted")

        case .disconnected(let reason, let code):
            print("DEBUG: Got disconnected reason = \(reason) code = \(code)")
            self.isConnected = false

        case .cancelled:
            print("DEBUG: cancelled.")
            // reconnect socket
            socket.connect()
            self.isConnected = true

        case .reconnectSuggested(let suggestReconnect):
            print("DEBUG: suggestReconnect = \(suggestReconnect)")
            // post notification that socket is not connected
            
        case .viabilityChanged(let viabilityChanged):
            print("DEBUG: viabilityChanged = \(viabilityChanged)")
            
        case .error(let error):
            print("DEBUG error: \(String(describing: error?.localizedDescription))")
            
        case .text(let socketString):
//            print("DEBUG: .text available")
            parseJSONSocketData(socketString)
            
        default:
            break
        }
    }
}

這是我的兩個自定義UIViewController類中的相關代碼行；

protocol CompanyPriceListDelegate: AnyObject {
    func sendPriceHistory(_ priceHistory: PriceHistory)
}

class CompanyPriceListVC: UITableViewController {
    
...
    
    let isConnected = Notification.Name(rawValue: isConnectedNotificationKey)
    let isNotConnected = Notification.Name(rawValue: isDisconnectedNotificationKey)
        
    override func viewDidLoad() {
        super.viewDidLoad()
        
...        
        createObservers()
...     
    }
    
    deinit {
        NotificationCenter.default.removeObserver(self)
    }
    
    private func createObservers() {
        print("DEBUG: createObservers() called")
        NotificationCenter.default.addObserver(self, selector: #selector(CompanyPriceListVC.dismissAndFetchStockInfo), name: isConnected, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(CompanyPriceListVC.notifyUserOnScreen(notification:)), name: isNotConnected, object: nil)
    }
    
    @objc private func fetchStockInfo() {
            NetworkServices.sharedInstance.fetchStockInfo(symbols: companyStockSymbols, delegate: self)
    }

    @objc private func notifyUserOnScreen(notification: NSNotification) {
        self.present(alertController, animated: true)
    }
    
    @objc public func dismissAndFetchStockInfo() {

        if presentedViewController == alertController {
            self.alertController.dismiss(animated: true, completion: nil)
        }
        fetchStockInfo()
    }
...
    
}

//
//  CompanyDetailsVC.swift
//  BetVictorTask
//
//  Created by Stephen Learmonth on 02/03/2022.
//

import UIKit

class CompanyDetailsVC: UIViewController {
    
...

    let isConnected = Notification.Name(rawValue: isConnectedNotificationKey)
    let isNotConnected = Notification.Name(rawValue: isDisconnectedNotificationKey)
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        configureNavigationBar()
        
        addSubViews()
        
        activateConstraints()
        
        createObservers()
        
        fetchCompanyDetails(symbol: symbol)
        
        let controller = navigationController?.viewControllers.first as! CompanyPriceListVC
        controller.delegate = self

    }
    
    deinit {
        NotificationCenter.default.removeObserver(self)
    }
    
    private func createObservers() {
        NotificationCenter.default.addObserver(self, selector: #selector(CompanyDetailsVC.dismissAndFetchCompanyDetails), name: isConnected, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(CompanyDetailsVC.notifyUserOnScreen(notification:)), name: isNotConnected, object: nil)
    }
    
    @objc private func dismissAndFetchCompanyDetails() {
        print("DEBUG: dismissAndFetchCompanyDetails() called")
        if presentedViewController == alertController {
            self.alertController.dismiss(animated: true, completion: nil)
        }
        
        fetchCompanyDetails(symbol: symbol)
    }

    @objc private func notifyUserOnScreen(notification: NSNotification) {
        print("DEBUG: notifyUserOnScreen(notification) called")
        self.present(alertController, animated: true)
    }
...
    
}

extension CompanyDetailsVC: CompanyPriceListDelegate {
    func sendPriceHistory(_ priceHistory: PriceHistory) {
        self.updatePrices(priceHistory)
    }
}

我正在真實設備上進行測試。

Answer 1

從 .cancelled 案例中刪除了 socket.connect()