title: how to download files from url and store in document folder
body: <p>I created one application that has two page (first page for show list of data and second page for show detail data).</p>
  
  <p>when click on any cell go to next page and in next page exists one button with name : DOWNLOAD
  that I want when I click on that button this file download and save in document folder.
  I dont know about it. please guide me that how download any file and store in document folder.
  I searching in internet but I dont understand about it.</p>
  
  <p>please tell me with code that how downloaded any file with one button. Im sorry if I not good english. </p>