Swift

NSURLSession类支持三种类型的任务：加载数据、下载和上传。下面通过样例分别进行介绍。

1，使用Data Task加载数据

使用全局的sharedSession()和dataTaskWithRequest方法创建。

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func sessionLoadData(){     //创建NSURL对象     let urlString:String="http://hangge.com"     let url:NSURL! = NSURL(string:urlString)     //创建请求对象     let request:NSURLRequest = NSURLRequest(URL: url)           let session = NSURLSession.sharedSession()         let dataTask = session.dataTaskWithRequest(request,         completionHandler: {(data:NSData!, response:NSURLResponse!, error:NSError!) -> Void in             if error != nil{                 print(error?.code)                 print(error?.description)             }else{                 let str = NSString(data: data!, encoding: NSUTF8StringEncoding)                 print(str)             }     }) as NSURLSessionTask           //使用resume方法启动任务     dataTask.resume()   }

2，使用Download Task来下载文件 

（1）不需要获取进度 

使用sharedSession()和downloadTaskWithRequest方法即可

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func sessionSimpleDownload(){     //下载地址     var url = NSURL(string: "http://hangge.com/blog/images/logo.png")     //请求     var request:NSURLRequest = NSURLRequest(URL: url!)           let session = NSURLSession.sharedSession()           //下载任务     var downloadTask = session.downloadTaskWithRequest(request,         completionHandler: { (location:NSURL!, response:NSURLResponse!, error:NSError!) -> Void in             //输出下载文件原来的存放目录             println("location:(location)")             //location位置转换             var locationPath = location.path             //拷贝到用户目录             let documnets:String = NSHomeDirectory() + "/Documents/1.png"             //创建文件管理器             var fileManager:NSFileManager = NSFileManager.defaultManager()             fileManager.moveItemAtPath(locationPath!, toPath: documnets, error: nil)             println("new location:(documnets)")     })           //使用resume方法启动任务     downloadTask.resume() }

（2）实时获取进度
需要使用自定义的NSURLSession对象和downloadTaskWithRequest方法

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import UIKit   class ViewController: UIViewController ,NSURLSessionDownloadDelegate {       override func viewDidLoad() {         super.viewDidLoad()                   sessionSeniorDownload()     }           //下载文件     func sessionSeniorDownload(){         //下载地址         var url = NSURL(string: "http://hangge.com/blog/images/logo.png")         //请求         var request:NSURLRequest = NSURLRequest(URL: url!)                   let session = currentSession() as NSURLSession                   //下载任务         var downloadTask = session.downloadTaskWithRequest(request)                   //使用resume方法启动任务         downloadTask.resume()     }           //创建一个下载模式     func currentSession() -> NSURLSession{         var predicate:dispatch_once_t = 0         var currentSession:NSURLSession? = nil                  dispatch_once(&predicate, {             var config = NSURLSessionConfiguration.defaultSessionConfiguration()             currentSession = NSURLSession(configuration: config, delegate: self, delegateQueue: nil)         })         return currentSession!     }           //下载代理方法，下载结束     func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask,         didFinishDownloadingToURL location: NSURL) {         //下载结束         println("下载结束")                   //输出下载文件原来的存放目录         println("location:(location)")         //location位置转换         var locationPath = location.path         //拷贝到用户目录         let documnets:String = NSHomeDirectory() + "/Documents/1.png"         //创建文件管理器         var fileManager:NSFileManager = NSFileManager.defaultManager()         fileManager.moveItemAtPath(locationPath!, toPath: documnets, error: nil)         println("new location:(documnets)")     }           //下载代理方法，监听下载进度     func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask,         didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {         //获取进度         var written:CGFloat = (CGFloat)(totalBytesWritten)         var total:CGFloat = (CGFloat)(totalBytesExpectedToWrite)         var pro:CGFloat = written/total         println("下载进度：(pro)")     }           //下载代理方法，下载偏移     func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask,         didResumeAtOffset fileOffset: Int64, expectedTotalBytes: Int64) {         //下载偏移，主要用于暂停续传     }       override func didReceiveMemoryWarning() {         super.didReceiveMemoryWarning()     } }

3，使用Upload Task来上传文件

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func sessionUpload(){     //上传地址     var url = NSURL(string: "http://hangge.com/")     //请求     var request:NSURLRequest = NSURLRequest(URL: url!)           let session = NSURLSession.sharedSession()           //上传数据流     let documents =  NSHomeDirectory() + "/Documents/1.png"     var imgData = NSData(contentsOfFile: documents)           var uploadTask = session.uploadTaskWithRequest(request, fromData: imgData) {         (data:NSData!, response:NSURLResponse!, error:NSError!) -> Void in         //上传完毕后         println("上传完毕")     }           //使用resume方法启动任务     uploadTask.resume() }