How to Get the Data from Nsurlsession.Sharedsession().Datataskwithrequest

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)
}

NSURLSession.sharedSession().dataTaskWithRequest(request) being executed last

This is simple example how to use completion :

func authorizeApigee(completion: (auth: Bool) -> Void) {
           // Send HTTP GET Request
    let scriptUrl = "https://fhirsandbox-prod.apigee.net/oauth/v2"
    let urlWithParams = scriptUrl + "/accesstoken?grant_type=client_credentials"
    let myUrl = NSURL(string: urlWithParams);

    let request = NSMutableURLRequest(URL:myUrl!);
    request.HTTPMethod = "POST"

    // Add Basic Authorization

    let username = "****"
    let password = "****"
    let loginString = NSString(format: "%@:%@", username, password)
    let loginData: NSData = loginString.dataUsingEncoding(NSUTF8StringEncoding)!
    let base64LoginString = loginData.base64EncodedStringWithOptions(NSDataBase64EncodingOptions())
    request.setValue(base64LoginString, forHTTPHeaderField: "Authorization")

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

        // Check for error
        if error != nil
        {
            self.errorApigee = 1
            print("error=\(error)")
             completion(auth: false)
        }

        // Print out response string
        let responseString = NSString(data: data!, encoding: NSUTF8StringEncoding)
        print("responseString = \(responseString)")
         completion(auth: true)
    }
    task.resume()
}

And how to use :

 self.authorizeApigee { (auth) -> Void in
        if (auth) {
           getHealthKitPermission()
        } else {
          //print errors
        }
    }

NSURLSession.sharedSession().dataTaskWithRequest runs slow in function

add this on you completionHandler ( it works if you update a view)

dispatch_async(dispatch_get_main_queue(), {
    if (error == nil) { ...... }
})

Advice 1:

return the task and use a completion param in your method,
you can cancel the task if it's too slow.

Advice 2 :
Use alamofire and swiftyJson framework

NSURLSession dataTaskWithRequest only works first time

Solved by Changing the cachePolicy

let request = NSMutableURLRequest(URL: NSURL(string: endPoint)!,
                                          cachePolicy: .ReloadIgnoringLocalAndRemoteCacheData,
                                          timeoutInterval: Constants.REQUEST.TIMEOUT)

Returning values URLSession.shared.dataTask in swift

You can use completion block to return value. Add completion block your to function like this

func parse (latitude: Double, longtitude: Double, completion: @escaping ((AnyObject) -> Void)){
    let jsonUrlString = "https://api.darksky.net/forecast/apiKey/\(latitude),\(longtitude)"

    guard let url = URL(string: jsonUrlString) else{
        return
    }

    var information: forecast?
    URLSession.shared.dataTask(with: url) { (data, res, err) in

        guard let data = data else { 
              return
        }

        do {
            let json = try JSONDecoder().decode(forecast.self, from: data)
            self.info = json
            completion(info)
        } catch {
            print("didnt work")
        }

    }.resume()

And when you call this function, it return your info

parse( lat, long, {info in
processJson(info)
})

running 2 tasks on one NSURLSession.sharedSession

Here is code sample which makes two requests:

//: Playground - noun: a place where people can play

import UIKit
import XCPlayground

XCPlaygroundPage.currentPage.needsIndefiniteExecution = true

let session = NSURLSession.sharedSession()

session.dataTaskWithURL(NSURL(string: "http://www.google.com")!, completionHandler: { (data :NSData?, response :NSURLResponse?, error :NSError?) -> Void in

        let res = NSString(data: data!, encoding: NSUTF8StringEncoding)
        print(res!)

        // make a new request here
        let innerSession = NSURLSession.sharedSession()

    innerSession.dataTaskWithURL(NSURL(string: "http://www.google.com")!, completionHandler: { (data :NSData?, response :NSURLResponse?, error :NSError?) -> Void in

        let res = NSString(data: data!, encoding: NSUTF8StringEncoding)
        print(res!)


    }).resume()


    }).resume()

Get the data from NSURLSession DownloadTaskWithRequest from completion handler

When using download tasks, generally one would simply use the location provided by the completionHandler of the download task to simply move the file from its temporary location to a final location of your choosing (e.g. to the Documents or Cache folder) using NSFileManager.

let task = NSURLSession.sharedSession().downloadTaskWithURL(url) { location, response, error in
    guard location != nil && error == nil else {
        print(error)
        return
    }

    let fileManager = NSFileManager.defaultManager()
    let documents = try! fileManager.URLForDirectory(.DocumentDirectory, inDomain: .UserDomainMask, appropriateForURL: nil, create: false)
    let fileURL = documents.URLByAppendingPathComponent("test.jpg")
    do {
        try fileManager.moveItemAtURL(location!, toURL: fileURL)
    } catch {
        print(error)
    }
}
task.resume()

You certainly could also load the object into a NSData using contentsOfURL. Yes, it works with local resources. And, no, it won't make another request ... if you look at the URL it is a file URL in your local file system. But you lose much of the memory savings of download tasks that way, so you might use a data task if you really wanted to get it into a NSData. But if you wanted to move it to persistent storage, the above pattern probably makes sense, avoiding using a NSData object altogether.

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