不使用共享会话
保留会话属性，使用此功能进行初始化。
init(configuration configuration: NSURLSessionConfiguration?, delegate delegate: NSURLSessionDelegate?, delegateQueue queue: NSOperationQueue?) -> NSURLSession
然后使用 dataTask 下载图片
在此委托方法中，您可以获得 响应
然后将 dataTask 更改为 downlaodTask
optional func URLSession(_ session: NSURLSession, dataTask dataTask: NSURLSessionDataTask, didReceiveResponse response: NSURLResponse, completionHandler completionHandler: (NSURLSessionResponseDisposition) -> Void)
示例代码：
import UIKitclass ViewController: UIViewController,NSURLSessionDelegate,NSURLSessionDataDelegate,NSURLSessionDownloadDelegate{ var session:NSURLSession? var dataTask:NSURLSessionDataTask? let url = NSURL(string:"http://www.zastavki.com/pictures/originals/2013/Photoshop_Image_of_the_horse_053857_.jpg")! var infoDic = NSMutableDictionary() override func viewDidLoad() { super.viewDidLoad() let configuration = NSURLSessionConfiguration.defaultSessionConfiguration() let manqueue = NSOperationQueue.mainQueue() session = NSURLSession(configuration: configuration, delegate:self, delegateQueue: manqueue) dataTask = session?.dataTaskWithRequest(NSURLRequest(URL: url)) dataTask?.resume() // Do any additional setup after loading the view, typically from a nib. } func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveResponse response: NSURLResponse, completionHandler: (NSURLSessionResponseDisposition) -> Void) { NSLog("%@",response.description) completionHandler(NSURLSessionResponseDisposition.BecomeDownload) } func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didBecomeDownloadTask downloadTask: NSURLSessionDownloadTask) { downloadTask.resume() } func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location: NSURL) { NSLog("%@",location); //Get response NSLog("%@", downloadTask.response!.description) }}
