//NSURLSession

/*

创建一个session ->创建一个task -> 启动task -> 处理回调

*/

//

class ViewController: UIViewController {

    override func viewDidLoad() {

        super.viewDidLoad()

       

        let session = NSURLSession.sharedSession()

        let dataTask = session.dataTaskWithURL(NSURL(string: " ")!, completionHandler: { (data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in

            //回调处理

            let json = try? NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions()) as! NSDictionary

            print("json:\(json)")

        })

      dataTask.resume()

    }