// MARK: - 同步请求
     func httpSynchronousRequest()
     {
         //创建NSURL对象
         var url:NSURL! = NSURL(string: "http://m.weather.com.cn/data/101010100.html")

         //创建请求对象
         var urlRequest : NSURLRequest = NSURLRequest(URL: url)

         //响应对象
         var response:NSURLResponse?

         //错误对象
         var error:NSError?

         //发出请求
         var data:NSData? = NSURLConnection.sendSynchronousRequest(urlRequest, returningResponse: &response, error: &error)

         if (error != nil)
         {
             println(error?.code)
             println(error?.description)
         }else
         {
             var jsonString = NSString(data: data!, encoding: NSUTF8StringEncoding)

             println(jsonString)
         }
     }

     // MARK: - 异步请求
     func httpAsynchronousRequest()
     {
         //创建NSURL对象
         var url:NSURL! = NSURL(string: "http://m.weather.com.cn/data/101010100.html")

         //创建请求对象
         var urlRequest : NSURLRequest = NSURLRequest(URL: url)

         //网络连接对象
 //        var conn : NSURLConnection? =  NSURLConnection(request: urlRequest, delegate: self)?

          //2015年5月2后修改
         var conn : NSURLConnection? =  NSURLConnection(request: urlRequest, delegate: self)

         conn?.scheduleInRunLoop(NSRunLoop.currentRunLoop(), forMode: NSRunLoopCommonModes)

         //执行
         conn?.start()
     }