Problems with prepareDesign method

Question

I have a problem guys, I’m new to Swift, and I have a method that takes a result from a JSON and I wanted to store it in a local variable and then pass this variable to a viewcontroller by next, however the variable when I pass the method prepareForSee it picks the variable as null or when I started it:

To explain better

1 - I installed a variable at the beginning of my view class "A"

var id = ""

2 - I made the Nsurlsession and took the json of a Rest per post and put inside the Dispatch to store in the variable that I installed.

func postQueEstouFazendo(v1: NSString, v2: NSString, v3: NSString)
{
    //url para aonde vou mandar o post
    let myUrl = NSURL(string: "http://minhapiqueestoupegando");   

    //inicia a variavel que vai fazer o request
    let request = NSMutableURLRequest(URL:myUrl!);

    //define o metodo do request
    request.HTTPMethod = "POST";// Compose a query string

    //coloca os dados em uma string de dados com um titulo
    let postString = "variavel=\(v1)&variavel2=\(v2)&variavel3=\(v3)";

    //define o encoding do que vai ser passado
    request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding);

    //inicia o envio dos dados
    let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
        data, response, error in           

        //se o erro de envio existir mostra um print
        if error != nil
        {
            print("error ao fazer o recolhimento =\(error)")

            return
        }           

        //aqui é a resposta do envio
        // You can print out response object
        print("response = \(response)")

        //aqui é uma outra forma mais completa de visualizar o retorno do envio
        // Print out response body
        let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)

        print("responseString = \(responseString)")

        //teste
        //Let's convert response sent from a server side script to a NSDictionary object:
        do
        {
            let myJSON =  try NSJSONSerialization.JSONObjectWithData(data!, options: .MutableContainers) as? NSDictionary

            if let parseJSON = myJSON
            {
                // Now we can access value of First Name by its key
                let idretorno = parseJSON["retorno"] as? String

                //faz a chamada da view voltando para a main thread!
                dispatch_async(dispatch_get_main_queue(), {
                      self. id = idretorno!
                })
            }
        }
        catch
        {
            print(error)
        }
    }

    task.resume() // fim do envio e volta pra thread principal ja que a task é uma background thread
}

3 - I made the method prepareForSegue and dentor it instanciei the Destination and put the value of the instantiated variable in view A for the variable I want to pass to view B

//Segues
override func shouldPerformSegueWithIdentifier(identifier: String, sender: AnyObject?) -> Bool {
  return true
}

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?){       
        if segue.identifier == "meuidentifier"
        {
          var viewA: viewB = segue.destinationViewController as! viewB
          viewA.idb = self.id
          viewA.outravariavel= 0
        }
    }

THAT LINE: viewA.idb = self.id

when you’re in this way prepareForSee it won’t that I’m picking it up in JSON it goes "" like when I instantiate.

Someone can help me?

Thank you!

Answer 1

The following must be happening before the request comes back. Try calling performSegueWithIdentifier within the request block, after the self.id = idretorno.

Answer 2

In the stretch below:

if let parseJSON = myJSON
{
  // Now we can access value of First Name by its key
  let idretorno = parseJSON["retorno"] as? String

  //faz a chamada da view voltando para a main thread!
  dispatch_async(dispatch_get_main_queue(), {
    self. id = idretorno!
  })
}

Try assigning the id variable before Dispatch, and check with Debug that the variable is being filled in.