為什么我的警報控制器沒有在我的Swift應用程式中關閉？-有解無憂

我有一個自定義視圖控制器類，當它收到來自我的網路服務類的未連接通知時，它會顯示一個警報控制器。當我收到來自網路服務類的進一步連接通知時，我想關閉警報控制器，但我無法關閉正在呈現的警報。

這是我的自定義視圖控制器類；

class CompanyPriceListVC: UITableViewController {
    
    // MARK: - Properties
    
    let companyStockSymbols = ["AAPL","AMZN", "MSFT", "GOOGL", "TSLA", "META","COINBASE:BTC", "BINANCE:BTCUSDT", "BINANCE:BNBBTC", "IC MARKETS:1", "IC MARKETS:2"]
    
    let defaultStockInfo = StockInfo(tradeConditions: nil, price: 0.00, symbol: "-", timestamp: 0.0, volume: 0.0)
    
    lazy var companyStockInfo = [StockInfo](repeating: defaultStockInfo, count: companyStockSymbols.count)
    
    var companyDetailsVC:CompanyDetailsVC?
    
    var tableRowSelected: Int?
    
    let defaultPriceHistory = PriceHistory(previous: nil, relative: 0.0, absolute: 0.0)
    
    lazy var priceHistory = [PriceHistory](repeating: defaultPriceHistory , count: companyStockSymbols.count)
    
    var deviceOrientation: Orientation = .portrait
    
    let activityIndicator: UIActivityIndicatorView = {
        let activityIndicator = UIActivityIndicatorView()
        activityIndicator.style = .large
        activityIndicator.hidesWhenStopped = true
        activityIndicator.color = .white
        activityIndicator.translatesAutoresizingMaskIntoConstraints = false
        activityIndicator.startAnimating()
        return activityIndicator
    }()
    
    let isConnected = Notification.Name(rawValue: isConnectedNotificationKey)
    let isNotConnected = Notification.Name(rawValue: isDisconnectedNotificationKey)
    
    let alertController = UIAlertController(title: "Connectivity Error", message: "Network connection lost. Please check your WiFi settings, mobile data settings or reception coverage.", preferredStyle: .alert)
    
    // MARK: - Lifecycle Methods
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        if UIDevice.current.orientation.isPortrait {
            self.deviceOrientation = .portrait
            self.tableView.register(CompanyStockCellPortrait.self, forCellReuseIdentifier: "CompanyStockCellPortrait")
        } else {
            self.deviceOrientation = .landscape
            self.tableView.register(CompanyStockCellLandscape.self, forCellReuseIdentifier: "CompanyStockCellLandscape")
        }
        
        configureNavigationBar()
        
        view.backgroundColor = .black
        
        configureTableView()
        
        configureConstraints()
        
        createObservers()
        
    }
    
    deinit {
        NotificationCenter.default.removeObserver(self)
    }
    
    private func createObservers() {
        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() {
        print("DEBUG: isBeingPresented: \(alertController.isBeingPresented)")
        if alertController.isBeingPresented {
            self.alertController.dismiss(animated: true, completion: nil)
        }
        fetchStockInfo()
    }
    
    override func willTransition(to newCollection: UITraitCollection, with coordinator: UIViewControllerTransitionCoordinator) {
        super.willTransition(to: newCollection, with: coordinator)
        
        coordinator.animate(alongsideTransition: { (context) in
            guard let windowInterfaceOrientation = self.windowInterfaceOrientation else { return }
            
            if windowInterfaceOrientation.isPortrait {
                self.deviceOrientation = .portrait
                self.tableView.register(CompanyStockCellPortrait.self, forCellReuseIdentifier: "CompanyStockCellPortrait")
                self.tableView.reloadData()
            } else {
                self.deviceOrientation = .landscape
                self.tableView.register(CompanyStockCellLandscape.self, forCellReuseIdentifier: "CompanyStockCellLandscape")
                self.tableView.reloadData()
            }
        })
    }
    
    private var windowInterfaceOrientation: UIInterfaceOrientation? {
        return self.view.window?.windowScene?.interfaceOrientation
    }
    
    // MARK: - TableView Data Source Methods
    
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return companyStockInfo.count
    }
    
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        
        switch deviceOrientation {
        case .portrait:
            let tableViewCellPortrait = tableView.dequeueReusableCell(withIdentifier: "CompanyStockCellPortrait", for: indexPath) as! CompanyStockCellPortrait
            
            tableViewCellPortrait.symbolValue.text = companyStockInfo[indexPath.row].symbol
            
            var latestPrice = companyStockInfo[indexPath.row].price
            latestPrice = round(latestPrice * 100.0) / 100.00
            tableViewCellPortrait.priceValue.text = String(format: "%.2f", arguments:[latestPrice])
            
            if let _ = priceHistory[indexPath.row].previous {
                
                let absoluteDifference = priceHistory[indexPath.row].absolute
                let relativeDifference = priceHistory[indexPath.row].relative
                
                if absoluteDifference > 0.0 {
                    tableViewCellPortrait.priceDirectionImageView.image = UIImage(systemName: "arrowtriangle.up.fill")
                    tableViewCellPortrait.priceDirectionImageView.tintColor = .systemGreen
                    tableViewCellPortrait.relativePriceDiffValue.text = String(format: "%.2f%%", arguments: [relativeDifference])
                    tableViewCellPortrait.relativePriceDiffValue.textColor = .systemGreen
                    tableViewCellPortrait.absolutePriceDiffValue.text = String(format: "(%.2f)", arguments: [absoluteDifference])
                    tableViewCellPortrait.absolutePriceDiffValue.textColor = .systemGreen
                } else if absoluteDifference < 0.0 {
                    tableViewCellPortrait.priceDirectionImageView.image = UIImage(systemName: "arrowtriangle.down.fill")
                    tableViewCellPortrait.priceDirectionImageView.tintColor = .systemRed
                    tableViewCellPortrait.relativePriceDiffValue.text = String(format: "%.2f%%", arguments: [relativeDifference])
                    tableViewCellPortrait.relativePriceDiffValue.textColor = .systemRed
                    tableViewCellPortrait.absolutePriceDiffValue.text = String(format: "(%.2f)", arguments: [absoluteDifference])
                    tableViewCellPortrait.absolutePriceDiffValue.textColor = .systemRed
                } else {
                    tableViewCellPortrait.priceDirectionImageView.image = UIImage(systemName: "diamond.fill")
                    tableViewCellPortrait.priceDirectionImageView.tintColor = .white
                    tableViewCellPortrait.relativePriceDiffValue.text = "0.00%"
                    tableViewCellPortrait.relativePriceDiffValue.textColor = .white
                    tableViewCellPortrait.absolutePriceDiffValue.text = "(0.00)"
                    tableViewCellPortrait.absolutePriceDiffValue.textColor = .white
                }
            } else {
                tableViewCellPortrait.priceDirectionImageView.image = UIImage()
                tableViewCellPortrait.priceDirectionImageView.tintColor = .white
                tableViewCellPortrait.relativePriceDiffValue.text = ""
                tableViewCellPortrait.absolutePriceDiffValue.text = ""
            }
            
            return tableViewCellPortrait
            
            
        case .landscape:
            
            let tableViewCellLandscape = tableView.dequeueReusableCell(withIdentifier: "CompanyStockCellLandscape", for: indexPath) as! CompanyStockCellLandscape
            
            tableViewCellLandscape.symbolValue.text = companyStockInfo[indexPath.row].symbol
            
            var latestPrice = companyStockInfo[indexPath.row].price
            latestPrice = round(latestPrice * 100.0) / 100.00
            tableViewCellLandscape.priceValue.text = String(format: "%.2f", arguments:[latestPrice])
            
            if let _ = priceHistory[indexPath.row].previous {
                
                let absoluteDifference = priceHistory[indexPath.row].absolute
                let relativeDifference = priceHistory[indexPath.row].relative
                
                if absoluteDifference > 0.0 {
                    tableViewCellLandscape.priceDirectionImageView.image = UIImage(systemName: "arrowtriangle.up.fill")
                    tableViewCellLandscape.priceDirectionImageView.tintColor = .systemGreen
                    tableViewCellLandscape.relativePriceDiffValue.text = String(format: "%.2f%%", arguments: [relativeDifference])
                    tableViewCellLandscape.relativePriceDiffValue.textColor = .systemGreen
                    tableViewCellLandscape.absolutePriceDiffValue.text = String(format: "(%.2f)", arguments: [absoluteDifference])
                    tableViewCellLandscape.absolutePriceDiffValue.textColor = .systemGreen
                } else if absoluteDifference < 0.0 {
                    tableViewCellLandscape.priceDirectionImageView.image = UIImage(systemName: "arrowtriangle.down.fill")
                    tableViewCellLandscape.priceDirectionImageView.tintColor = .systemRed
                    tableViewCellLandscape.relativePriceDiffValue.text = String(format: "%.2f%%", arguments: [relativeDifference])
                    tableViewCellLandscape.relativePriceDiffValue.textColor = .systemRed
                    tableViewCellLandscape.absolutePriceDiffValue.text = String(format: "(%.2f)", arguments: [absoluteDifference])
                    tableViewCellLandscape.absolutePriceDiffValue.textColor = .systemRed
                } else {
                    tableViewCellLandscape.priceDirectionImageView.image = UIImage(systemName: "diamond.fill")
                    tableViewCellLandscape.priceDirectionImageView.tintColor = .white
                    tableViewCellLandscape.relativePriceDiffValue.text = "0.00%"
                    tableViewCellLandscape.relativePriceDiffValue.textColor = .white
                    tableViewCellLandscape.absolutePriceDiffValue.text = "(0.00)"
                    tableViewCellLandscape.absolutePriceDiffValue.textColor = .white
                }
            } else {
                tableViewCellLandscape.priceDirectionImageView.image = UIImage()
                tableViewCellLandscape.priceDirectionImageView.tintColor = .white
                tableViewCellLandscape.relativePriceDiffValue.text = ""
                tableViewCellLandscape.absolutePriceDiffValue.text = ""
            }
            
            return tableViewCellLandscape
            
        }
    }
    
    // MARK: - TableView Delegate Methods
    
    override func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return 100.0
    }
    
    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        companyDetailsVC = CompanyDetailsVC(companyStockInfo: companyStockInfo[indexPath.row])
        tableRowSelected = indexPath.row
        navigationController?.pushViewController(companyDetailsVC!, animated: true)
    }
    
    // MARK: - Helper Functions
    
    private func configureNavigationBar() {
        UINavigationBar.appearance().titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white]
        navigationController?.navigationBar.topItem?.title = "Trade Tracker"
        navigationController?.navigationBar.barStyle = .black
        navigationController?.navigationBar.prefersLargeTitles = true
    }
    
    private func configureTableView() {
        tableView.delegate = self
        tableView.dataSource = self
        tableView.separatorStyle = .singleLine
        tableView.separatorColor = .white
        tableView.tableFooterView = UIView()
    }
    
    private func configureConstraints() {
        tableView.addSubview(activityIndicator)
        
        NSLayoutConstraint.activate([
            activityIndicator.centerXAnchor.constraint(equalTo: tableView.centerXAnchor),
            activityIndicator.topAnchor.constraint(equalTo: tableView.topAnchor, constant: 250)
        ])
        
        tableView.layoutSubviews()
    }
}

// MARK: - Network Service Delegate Method

extension CompanyPriceListVC: NetworkServicesDelegate {
    
    func sendStockInfo(stocksInfo: [String : StockInfo]) {
        
        DispatchQueue.main.async {
            
            // Compute absolute and relative price differences
            for (index, symbol) in self.companyStockSymbols.enumerated() {
                if stocksInfo[symbol] != nil {
                    self.priceHistory[index].previous = self.companyStockInfo[index].price
                    self.companyStockInfo[index] = stocksInfo[symbol]!
                    
                    var latestPrice = self.companyStockInfo[index].price
                    latestPrice = round(latestPrice * 100.0) / 100.00
                    
                    if let previous = self.priceHistory[index].previous {
                        let previousPrice = round(previous * 100.0) / 100.0
                        var absoluteDifference = latestPrice - previousPrice
                        absoluteDifference = round(absoluteDifference * 100.0) / 100.0
                        self.priceHistory[index].absolute = absoluteDifference
                        
                        var relativeDifference = 0.0
                        if previousPrice != 0.00 {
                            relativeDifference = (absoluteDifference / previousPrice) * 100.0
                            relativeDifference = round(relativeDifference * 100) / 100.0
                        }
                        self.priceHistory[index].relative = relativeDifference
                    }
                }
            }
            
            self.tableView.reloadData()
            self.activityIndicator.stopAnimating()
                        
            guard let rowSelected = self.tableRowSelected else { return }
            self.companyDetailsVC!.companyStockInfo = self.companyStockInfo[rowSelected]
            self.companyDetailsVC!.relativeDifference = self.priceHistory[rowSelected].relative
            self.companyDetailsVC!.absoluteDifference = self.priceHistory[rowSelected].absolute
            
        }
    }
}

這是我的網路服務課程；

import UIKit
import Starscream
import Network

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

final class NetworkServices {
    
    static let sharedInstance = NetworkServices()
        
    var request = URLRequest(url: FINNHUB_SOCKET_STOCK_INFO_URL!)
    var socket: WebSocket!
    public private(set) var isConnected = false
 
    var stocksInfo: [String: StockInfo] = [:]
    
    var socketResults: [String: [StockInfo]] = [:]
    
    weak var delegate: NetworkServicesDelegate?
        
    var stockSymbols: [String] = []
    
    private init() {
        request.timeoutInterval = 5
        socket = WebSocket(request: request)
        socket.delegate = self
    }
    
    private let queue = DispatchQueue.global()
    
    private let monitor = NWPathMonitor()
    
    public func startMonitoring() {
        monitor.start(queue: queue)
        
        self.monitor.pathUpdateHandler = { [weak self] path in
            if path.status == .satisfied {
                // connect the socket
                self?.socket.connect()
            } else {
                // disconnect the socket
                self?.socket.disconnect()
                // post notification that socket is now disconnected
                DispatchQueue.main.async {
                    let name = Notification.Name(rawValue: isDisconnectedNotificationKey)
                    NotificationCenter.default.post(name: name, object: nil)
                }
            }
        }
        
    }
    
    public func stopMonitoring() {
        monitor.cancel()
    }
    
    func fetchStockInfo(symbols: [String], delegate: CompanyPriceListVC) {
                
        stockSymbols = symbols
        
        self.delegate = delegate
                
        for symbol in symbols {
            
            let string = FINNHUB_SOCKET_MESSAGE_STRING   symbol   "\"}"
            
            socket.write(string: string)

        }
    }

    private func parseJSONSocketData(_ socketString: String) {
        
        self.socketResults = [:]
        self.stocksInfo = [:]
        
        let decoder = JSONDecoder()
        do {
            let socketData = try decoder.decode(SocketData.self, from: socketString.data(using: .utf8)!)
            guard let stockInfoData = socketData.data else { return }
            for stockInfo in stockInfoData {
                let symbol = stockInfo.symbol
                if self.socketResults[symbol] == nil {
                    self.socketResults[symbol] = [StockInfo]()
                }
                self.socketResults[symbol]?.append(stockInfo)
            }
            
            for (symbol, stocks) in self.socketResults {
                for item in stocks {
                    if self.stocksInfo[symbol] == nil {
                        self.stocksInfo[symbol] = item
                    } else if item.timestamp > self.stocksInfo[symbol]!.timestamp {
                        self.stocksInfo[symbol] = item
                    }
                }
            }
            self.delegate?.sendStockInfo(stocksInfo: self.stocksInfo)
            
        } catch {
            print("DEBUG: error: \(error.localizedDescription)")
        }
    }
    
    func fetchCompanyInfo(symbol: String, completion: @escaping (CompanyInfo?, UIImage?)->()) {
        
        let urlString = FINNHUB_HTTP_COMPANY_INFO_URL_STRING   symbol   "&token="   FINNHUB_API_TOKEN
        
        guard let url = URL(string: urlString) else { return }
        
        let task = URLSession.shared.dataTask(with: url) { data, response, error in
            if let error = error {
                print("Error fetching company info: \(error)")
            }
            guard let data = data else { return }
            let decoder = JSONDecoder()
            
            do {
                let companyInfo = try decoder.decode(CompanyInfo.self, from: data)
                
                guard let logoURL = URL(string: companyInfo.logo) else { return }
                
                let task = URLSession.shared.dataTask(with: logoURL) { data, response, error in
                    if let error = error {
                        print("Error fetching logo image: \(error)")
                    }
                    guard let data = data else { return }
                    
                    guard let logoImage = UIImage(data: data) else { return }
                    
                    completion(companyInfo, logoImage)
                    
                }
                task.resume()
            } catch {
                print("Error decoding JSON: \(error)")
                completion(nil, nil)
            }
        }
        task.resume()
    }
}

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)

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

        case .cancelled:
            print("DEBUG: cancelled.")
            // post notification that socket is not connected

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

我試過查詢isBeingPresented警報控制器的屬性，但它總是測驗為假，即使我可以看到警報控制器正在呈現。

uj5u.com熱心網友回復：

您可以檢查當前顯示UIViewController的內容是否實際上是alertController這樣的：

@objc public func dismissAndFetchStockInfo() {
    if presentedViewController == alertController {
        alertController.dismiss(animated: true, completion: nil)
    }

    fetchStockInfo()
}

這是因為isBeingPresented僅在view[Will|Did][Disa|A]ppear方法內部有效。

轉載請註明出處，本文鏈接：https://www.uj5u.com/caozuo/452278.html

標籤：迅速代码 uialert控制器

上一篇：SwiftUI：匹配幾何效果不起作用

下一篇：MacOSswiftUI表格選擇單項