title: What is difference between NSURLSessionDataTask vs NSURLSessionDownloadTask
body: <p>In latest apple introduce new <code>NSURLSession</code> in replace of <code>NSURLConnection</code>, so in there are different task , so what is the difference between <code>NSURLSessionDataTask</code>, <code>NSURLSessionDownloadTask</code> ?</p>
  
  <p>and in which scenario use <code>NSURLSessionTask</code> and where <code>NSURLSessionDownloadTask</code>?</p>