title: How to convert NSDictionary to Json String in Swift ( iOS, Xcode )?
body: <p>I'm suffering from the following problem....
  My  <code>NSDictionary</code> is like that :</p>
  
  <pre><code>var dic : NSDictionary = [ "level" :
      [
          ["column" : 0,"down" : 0,"left" : 0,"right" : 0,"row" : 0,"up" : 0],
          ["column" : 1,"down" : 0,"left" : 0,"right" : 0,"row" : 0,"up" : 0],
          ["column" : 2,"down" : 0,"left" : 0,"right" : 0,"row" : 0,"up" : 0],
          ["column" : 0,"down" : 0,"left" : 0,"right" : 0,"row" : 1,"up" : 0],
          ["column" : 1,"down" : 0,"left" : 0,"right" : 0,"row" : 1,"up" : 0],
          ["column" : 2,"down" : 0,"left" : 0,"right" : 0,"row" : 1,"up" : 0]
      ]
  ]
  </code></pre>
  
  <p>But If I print this,</p>
  
  <pre><code>print(dic);  or print(“\(dic)”);
  </code></pre>
  
  <p>The Out put Is like that :</p>
  
  <pre><code>{
      level =     (
                  {
              column = 0;
              down = 0;
              left = 0;
              right = 0;
              row = 0;
              up = 0;
          },
                  {
              column = 1;
              down = 0;
              left = 0;
              right = 0;
              row = 0;
              up = 0;
          },
                  {
              column = 2;
              down = 0;
              left = 0;
              right = 0;
              row = 0;
              up = 0;
          },
                  {
              column = 0;
              down = 0;
              left = 0;
              right = 0;
              row = 1;
              up = 0;
          },
                  {
              column = 1;
              down = 0;
              left = 0;
              right = 0;
              row = 1;
              up = 0;
          },
                  {
              column = 2;
              down = 0;
              left = 0;
              right = 0;
              row = 1;
              up = 0;
          }
      ); }
  </code></pre>
  
  <p>How Can I get exact Json String? 
  In swift, xcode?</p>