Autocomplete with NSURLSession doesn't work well with slow internet connection

Question

I have a searchBar. When you type in the searchBar(at least 3 character) a request with the searchString is sent to a server. This server response with a XML. This XML is parsed. A list is displayed to the user.

Each time the user type in the searchBar a new request is sent and a new list is displayed.

This is part of my code:

let url = NSURL(string: "\(Paises.sharedInstance.getUrlPaisActual())?tipo=3&v=3&p=\(Paises.sharedInstance.getIdPaisActual())&texto=\(searchString)")

let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {(data, response, error) in
    let parser = NSXMLParser(data: data)
    parser.delegate = self
    parser.parse()
}

task.resume()

This work well when the network is fine. But when the network is slow, the responses don't arrive in the same order in which they are submitted.

How can I fix this? Can I know if a response is outdated? Maybe with a timeout?

Thanks.

Updated with Wain's answer:

This is the static var where I store my token.

struct RequestToken {
    static var identificador = 0

    func incrementar() -> Int {
        return ++RequestToken.identificador
    }
}

This is the new request:

let url = NSURL(string: "\(Paises.sharedInstance.getUrlPaisActual())?tipo=3&v=3&p=\(Paises.sharedInstance.getIdPaisActual())&texto=\(searchString)")

let identificador = RequestToken().incrementar()

let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {(data, response, error) in

    if identificador ==  RequestToken.identificador {
        let parser = NSXMLParser(data: data)
        parser.delegate = self
        parser.parse()
    }
}

task.resume()

Thank you very much Wain.

score 1 · Accepted Answer · answered Apr 10 '15 at 11:08

Rather than a timeout you can create a session token that is captured by the block, then, before the parser is started and the data processed and returned you can check that the session token is still valid. Each time you start a request, store the session token in an instance variable so you can compare it with the token captured by the block.

Autocomplete with NSURLSession doesn't work well with slow internet connection

1 Answers1