title: How to encrypt string using lib-sodium in iOS
body: <p>I have scanned a <code>QR</code> Code image using <code>ZXingWidget</code> lib, received a string as response.
  Now I want to encrypt that string using <code>lib-sodium</code> in iOS.</p>
  
  <p>Any suggestion how to do string encryption in iOS using <code>lib-sodium</code> library....
  Thanks in advance...</p>