如何从NSURLSession.sharedSession().dataTaskWithReques

Question

如何从NSURLSession.sharedSession().dataTaskWithReques

class PostFOrData {
    let url = NSURL( string: "http://210.61.209.194:8088/SmarttvWebServiceTopmsoApi/GetReadlist")
    var picUrl = NSURL(string : "http://210.61.209.194:8088/SmarttvMedia/img/epi00001.png")
    var responseString : NSString = ""

    func forData() -> NSString {

        let request = NSMutableURLRequest( URL: url!)
        request.HTTPMethod = "POST"
        var s : NSString = ""

        let postString : String = "uid=59"
        request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)

        let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
            data, response, error in

            if error != nil {
                println("error=\(error)")
                return
            } else {
                println("response = \(response!)")
                self.responseString = NSString(data: data, encoding: NSUTF8StringEncoding)!
                println("responseString = \(self.responseString)")
            }

        }

        // I want to return NSString here, but I always get nothing
        return self.responseString    }}

有人知道如何从任务中获取数据吗？