NWConnection Timeout

Question

PrinzAkim OP

Created Sep ’20

Replies 5

Boosts 0

Views 3.9k

Participants 4

I am using Apples Network framework to build a TCP connection to a server. It locks like this:

Code Block let testConnection = NWConnection(host: NWEndpoint.Host(server!.serverAddress), port: NWEndpoint.Port(server!.serverPort)!, using: .tcp)testConnection.stateUpdateHandler = ({ state in
        print("TCP state change to: \(state)")
        switch state {
        case .setup:
            break
        case .waiting(let error):
            print("Waiting Error \(error)")
            testConnection.cancel()
            break
        case .preparing:
            break
        case .ready:
            beginCommunication()
            break
        case .failed(let error):
            print("\(error)")
            break
        case .cancelled:
            break
        default:
            break
        }
    })

The serverAddress and serverPort is entered by the user. I want to test the connection. Now my problem is, that if the user is entering an invalid address / port combination (the service is not offered by the server). I stuck in the preparing state for quite a long time. After that I get to the waiting stage (with error message POSIXErrorCode: Operation timed out).
Is there any way to set the timeout for this first connection process ?
Thanks for your ideas

Answered by DTS Engineer in 637497022

The NWConnection API is inherently asynchronous. If you want a custom timeout, just use a timer.

Having said that, I’m going to caution you against setting the timeout too low. There’s nothing more annoying that seeing a connection time out just as it was about to complete. The default timeouts are long (generally in the 30 to 75 second range) for a reason.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@apple.com"

Boost

Answer 1

OOPer OP

Sep ’20

Is there any way to set the timeout for this first connection process ?

I'm just watching the documentations and not tested, but NWProtocolTCP.Options has a parameter named connectionTimeout.

Can't you use it?

0

Answer 2

PrinzAkim OP

Sep ’20

Thanks OOPer,

this I had tried, but it seem that this is a timeout for the established TCP-connection, but I am one layer above in which the server is not answering because the port is wrong....

0

Answer 3

DTS Engineer OP

Apple

Sep ’20

Accepted Answer

The NWConnection API is inherently asynchronous. If you want a custom timeout, just use a timer.

Having said that, I’m going to caution you against setting the timeout too low. There’s nothing more annoying that seeing a connection time out just as it was about to complete. The default timeouts are long (generally in the 30 to 75 second range) for a reason.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@apple.com"

0

Answer 4

PrinzAkim OP

Oct ’20

Thanks, eskimo!
I have tied the timer which works.

But since in the application this problem only appears in a kind of connection test process I decided to start the connection and show an ALERT with CANCEL button. The ALERT will be closed on reaching .cancelled state. Connection is cancelled on state .ready, .waiting and .failure as well as when CANCEL is pressed. The I inform the main thread about the result by a Notification:

Code Block func showTestingAlert () {        if alert == nil {
            alert = UIAlertController(title: "Test connection", message: "Please wait...", preferredStyle: .alert)
 
            if let alert = alert {
                alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: { action in
                    self.testConnection.forceCancel()
                    NotificationCenter.default.post(name: Notification.Name("connectionTest"), object: "Canceled by user!")
                    self.alert = nil
                    return
                }))
                let loadingIndicator = UIActivityIndicatorView(frame: CGRect(x: 10, y: 5, width: 50, height: 50))
                loadingIndicator.hidesWhenStopped = true
                loadingIndicator.style = UIActivityIndicatorView.Style.medium
                loadingIndicator.startAnimating()
                alert.view.addSubview(loadingIndicator)
                present(alert, animated: false, completion: nil)
			}
        }
    }

0

Answer 5

MrEssen OP

Dec ’20

You can indeed use NWProtocolTCP.Options to set a connection timeout like this:

Code Block 	let options = NWProtocolTCP.Options()
	options.connectionTimeout = 2
	let params = NWParameters(tls: nil, tcp: options)
	let connection = NWConnection(host: anyHost, port: anyPort, using: params)

So, no timer is needed.

0