Encode String with Escape Code

NSString * str = @"q=你好&p=ac";
 
 NSString * escapeEncoded = [str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

/* escapeEncoded's content:
     q=%E4%BD%A0%E5%A5%BD&p=ac
 */
  NSString * unEscaped = [escapeEncoded stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

/*unEscaped's content:

　　q=你好&p=ac

 */