iOS Swift connect WiFi programmatically and distinguish between bad password and no WiFi in range

Question

NEHotspotConfiguration works well, but the error is nil both when the SSID I am trying to connect to is not available (out of range or off) or when the password I've submitted is incorrect.

What am I doing wrong? I want to be able to distinguish between these two scenarios so I can inform the user accordingly.

Code snippet:

func connect(ssid: String, password: String, completionHandler: @escaping(Bool?, String?) -> Void) {
    activityIndicatorView?.startAnimating()

    guard !isAlreadyConnected(ssid: ssid) else {
        activityIndicatorView?.stopAnimating()
        completionHandler(true, nil)
        return;
    }

    let hotspotConfig = NEHotspotConfiguration(ssid: ssid, passphrase: password, isWEP: false)//Secured connections
    hotspotConfig.joinOnce = true

    NEHotspotConfigurationManager.shared.apply(hotspotConfig) {[weak self] (error) in
        guard let self = self else { return; }

        self.activityIndicatorView?.stopAnimating()
        if let error = error {
            completionHandler(false, error.localizedDescription)
        }
        else {
            let ssids = self.currentSSIDs()
            if ssids.count > 0 && ssids.first == ssid {
                completionHandler(true, nil)
            } else {
                completionHandler(false, error?.localizedDescription ?? "An error occured")
            }
        }
    }
}

Answer 1

Quickly tried it and it is perfectly reproducible it seems. Further research revealed that it is an Apple error. So the answer is: You are nothing doing wrong, it's a bug.

Reasons seems to be:

...the errors that you see via the completion handler are those errors related to the framework itself. Once the request has made it past the Network Extension framework, down to the Wi-Fi subsystem, errors are displayed to the user rather than delivered to your completion handler. Whether that’s a bug is up for debate.

Later down one can read:

So my 2 bugs (46628017 and 46579891) regarding the NEHotspot marked as duplicated of 42919071

see the whole discussion here: https://forums.developer.apple.com/thread/96834

Some Experiment

There is this nice SO answer: https://stackoverflow.com/a/5198968/2331445

It shows how to access information about the currently connected WIFI.

As the author explains, you need to add the Access WiFi Information capability for iOS > 12. A test using the getConnectedWifiInfo method from the above SO answer for an experiment might look like this:

import UIKit
import NetworkExtension
import SystemConfiguration.CaptiveNetwork

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    @IBAction func onConnect(_ sender: Any) {
        let configuration = NEHotspotConfiguration.init(ssid: "somessid", passphrase: "somepassphrase", isWEP: false)
        configuration.joinOnce = true

        NEHotspotConfigurationManager.shared.apply(configuration) { [weak self] (error) in
            print("error is \(String(describing: error))")
            if let error = error {
                let nsError = error as NSError
                if nsError.domain == "NEHotspotConfigurationErrorDomain" {
                    if let configError = NEHotspotConfigurationError(rawValue: nsError.code) {
                        switch configError {
                        case .invalidWPAPassphrase:
                            print("password error: \(error.localizedDescription)")
                        case .invalid, .invalidSSID, .invalidWEPPassphrase,
                             .invalidEAPSettings, .invalidHS20Settings, .invalidHS20DomainName, .userDenied, .pending, .systemConfiguration, .unknown, .joinOnceNotSupported, .alreadyAssociated, .applicationIsNotInForeground, .internal:
                            print("other error: \(error.localizedDescription)")
                        @unknown default:
                            print("later added error: \(error.localizedDescription)")
                        }
                    }
                } else {
                    print("some other error: \(error.localizedDescription)")
                }
            } else {
                print("perhaps connected")

                self?.printWifiInfo()
            }
        }

    }

    @IBAction func onInfo(_ sender: Any) {
        self.printWifiInfo()
    }

    private func printWifiInfo() {
        print("printWifiInfo:")
        if let wifi = self.getConnectedWifiInfo() {
            if let connectedSSID = wifi["SSID"] {
                print("we are currently connected with \(connectedSSID)")
            }
            print("further info:")
            for (k, v) in wifi {
                print(".  \(k) \(v)")
            }
        }
        print()
    }

    private func getConnectedWifiInfo() -> [AnyHashable: Any]? {
        if let ifs = CFBridgingRetain( CNCopySupportedInterfaces()) as? [String],
            let ifName = ifs.first as CFString?,
            let info = CFBridgingRetain( CNCopyCurrentNetworkInfo((ifName))) as? [AnyHashable: Any] {            
                return info
            }
        return nil
    }

}

And indeed if I run this code I get as result:

error is nil
perhaps connected
printWifiInfo:
we are currently connected with somessid
further info:
.  SSIDDATA <11111111 22222222 333331333 44444444 55>
.  BSSID 70:33:ab:cd:ef:22
.  SSID somessid

The author of this SO answer also shows methods for older iOS versions.