How can I get the Data from NSURLSession.sharedSession().dataTaskWithRequest

You can't return data directly from an asynchronous task.

The solution with Swift 2 is to make a completion handler like this:

class PostFOrData {
    // the completion closure signature is (NSString) -> ()
    func forData(completion: (NSString) -> ()) {
        if let url = NSURL(string: "http://210.61.209.194:8088/SmarttvWebServiceTopmsoApi/GetReadlist") {
            let request = NSMutableURLRequest( URL: url)
            request.HTTPMethod = "POST"
            let postString : String = "uid=59"
            request.HTTPBody = postString.dataUsingEncoding(NSUTF8StringEncoding)
            let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {
                data, response, error in
                if let data = data,
                    jsonString = NSString(data: data, encoding: NSUTF8StringEncoding)
                    where error == nil {
                        completion(jsonString)
                } else {
                    print("error=\(error!.localizedDescription)")
                }
            }
            task.resume()
        }
    }
}


let pfd = PostFOrData()

// you call the method with a trailing closure
pfd.forData { jsonString in
    // and here you get the "returned" value from the asynchronous task
    print(jsonString)
}

That way, the completion is only called when the asynchronous task is completed. It is a way to "return" the data without actually using return.

Swift 3 version

class PostFOrData {
    // the completion closure signature is (String) -> ()
    func forData(completion:  @escaping (String) -> ()) {
        if let url = URL(string: "http://210.61.209.194:8088/SmarttvWebServiceTopmsoApi/GetReadlist") {
            var request = URLRequest(url: url)
            request.httpMethod = "POST"
            let postString : String = "uid=59"
            request.httpBody = postString.data(using: String.Encoding.utf8)
            let task = URLSession.shared.dataTask(with: request) {
                data, response, error in
                if let data = data, let jsonString = String(data: data, encoding: String.Encoding.utf8), error == nil {
                    completion(jsonString)
                } else {
                    print("error=\(error!.localizedDescription)")
                }
            }
            task.resume()
        }
    }
}


let pfd = PostFOrData()

// you call the method with a trailing closure
pfd.forData { jsonString in
    // and here you get the "returned" value from the asynchronous task
    print(jsonString)
}