Can someone help me to figure how to resolve the following runtime error?

The valueForKeyPath() method is part of NSKeyValueCoding

"The

NSKeyValueCoding

The error is telling you that NSData (which happens to be an instance of NSConcreteMutableData in this case) doesn't have a responseData property, and asking for an undefined property is a programmer error.

I'm not familiar with AlamoFire, but did you mean to use some other similarly named method, or need to convert the raw data into another object somehow?

Hi, LCS.

Thanks for the Help here. AlamoFire is a library I used in my code to make a HTTP GET. The codes I pasted above was truncated. Here's the complete text:

let parameters = ["q":textToTranslate,

"langpair":"en|es"]

Alamofire.request(.GET, "http://api.mymemory.translated.net/get", parameters:parameters)

.response { (_, _, data, _) in

let translatedText: String? = data?.valueForKeyPath("responseData.translatedText") as! String?

if let translated :String = translatedText{

self.textView.text = translated

} else {

self.textView.text = "No translation available."

}

I send a Get request to http://api.mymemory.translated.net/ to translate a string from English to Spanish. I am expecting a string (translation) from the data?.valueForKeyPath. The app crached in valueForKeyPath. What other method would you suggest me to use? Thanks in Advanced.

The 'data' you are getting is just raw data stored in an NSData instance. That instance doesn't know anything about the format of whatever is stored in it, and using KVC's valueForKeyPath(...) isn't going to be able to access anything in that raw data.

Maybe you should be using .responseJSON() instead of .response() so that you get a JSON dictionary instead of raw data?

This code returns the result as in the comment:

    var session: NSURLSession = NSURLSession.sharedSession()
    @IBAction func doTranslate(_: AnyObject) {
        let textToTranslate = "What other method would you suggest me to use?"
        let parameters = ["q": textToTranslate,
            "langpair": "en|es"]
        func escapeQuery(str: String) -> String {
            return str.stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.URLQueryAllowedCharacterSet())!
        }
        let query = parameters.map {"\($0)=\(escapeQuery($1))"}.joinWithSeparator("&")
        let url = NSURL(string: "http:...") //fill the same url
        let request = NSURLRequest(URL: url)
        let task = session.dataTaskWithRequest(request) {data, response, error in
            if let
                json = try? NSJSONSerialization.JSONObjectWithData(data!, options: []),
                jsonObject = json as? NSDictionary,
                responseData = jsonObject["responseData"] as? NSDictionary,
                translatedText = responseData["translatedText"] as? String
            {
                print(translatedText) //->¿Qué otro método ¿usted me sugieren usar?
            }
        }
        task.resume()
    }

I don't know what Alamofire is, but I guess you need to:

- Parse `data` as JSON yourself

or

- Tell the Alamofire thing to return the data as JSON

To find what you need to do, insert the following two lines after `(_, _, data, _) in`:

print(data)
print(data.dynamicType)

EDIT: added comment for the deleted url.