无法调用非函数类型'JSON'的值，如何从Swift中的块返回值

Question

I have a function:

func connectToWS(callback: (JSON)) -> Void {
    let urlPath: String = "http://xxx.webservice.com"
    let url: NSURL = NSURL(string: urlPath)!
    let request: NSURLRequest = NSURLRequest(URL: url)

    let session = NSURLSession.sharedSession()
    let task = session.dataTaskWithRequest(request){
        (data, response, error) -> Void in
        if error != nil {

        } else {
            let json:JSON = JSON(data: data!)
            // RETURN?
        }
    }
    task.resume()
}

All I'm trying to do is to return the NSDictionary JSON serialized dictionary when I call this function. But it seems like I can't because my json data is in the dataTaskWithRequest block. I've tried using call back but it shows the error:

Cannot call value of non-function type 'JSON'

Can anyone point me in the direction to solve this?

I am using SwiftyJSON as a 3rd party library.

Answer 1

Try this out:

func connectToWS(callBack: ((data: NSData!, response: NSURLResponse!, error: NSError!) -> Void)?) {
    let urlPath: String = "http://xxx.webservice.com"
    let url: NSURL = NSURL(string: urlPath)!
    let request: NSURLRequest = NSURLRequest(URL: url)
    let session = NSURLSession.sharedSession()

    let task = session.dataTaskWithRequest(request) { data, response, error in
        callBack?(data: data, response: response, error: error)
        return
    }

    task.resume()
}

Then call this like:

connectToWS() { data, response, error in
    if error != nil {
        if error.domain == NSURLErrorDomain && error.code == NSURLErrorTimedOut {
            print("timed out") // note, `response` is likely `nil` if it timed out
        }
    }
}