Why is my alert controller not dismissing in my Swift app? - swift

Question

I have a custom view controller class which presents an alert controller when it receives a not connected notification from my network services class. I want to dismiss the alert controller when I receive a further connected notification from the network services class but I am unable to dismiss the presenting alert.
Here is my custom view controller class;
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
}
}
}
and here is my network services class;
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
}
}
}
I've tried querying the isBeingPresented property of the alert controller but it always tests as false even though I can see the alert controller is being presented.

Answer 1

You could do a check if the currently presented UIViewController is actually the alertController like this:
#objc public func dismissAndFetchStockInfo() {
if presentedViewController == alertController {
alertController.dismiss(animated: true, completion: nil)
}
fetchStockInfo()
}
This is because isBeingPresented is only valid inside the view[Will|Did][Disa|A]ppear methods.