title: encoding '+' character on a NSURLRequest
body: <p>I am loading a webView with an external url and post data.</p>
  
  <p>Everything works fine, unless the data contains the '+' character, then it fails.
  I've tried to encode the data in differents ways but I can't make it work. 
  How can I correctly encode the plus character?</p>
  
  <pre><code>-(void) cargarWebViewTPVRedys:(TPVRedsys*) redsys{
  
      NSURL *url = [NSURL URLWithString: @"https://sis-t.redsys.es:25443/sis/realizarPago"]; // PRUEBAS
      // NSURL *url = [NSURL URLWithString: @"https://sis.redsys.es/sis/realizarPago"];     // REAL
      NSString *body = [NSString stringWithFormat: @"DS_SIGNATURE=%@&amp;DS_MERCHANTPARAMETERS=%@&amp;DS_SIGNATUREVERSION=%@",redsys.Ds_Signature,redsys.Ds_MerchantParameters,redsys.Ds_SignatureVersion];
      NSMutableURLRequest *request = [[NSMutableURLRequest alloc]initWithURL: url];
      [request setHTTPMethod: @"POST"];
      //[request setHTTPBody: [body dataUsingEncoding: NSUnicodeStringEncoding]];
      //[request setHTTPBody: [body dataUsingEncoding: NSASCIIStringEncoding]];
      [request setHTTPBody: [body dataUsingEncoding: NSUTF8StringEncoding allowLossyConversion:false]];
      NSLog(redsys.Ds_Signature);
      NSLog(redsys.Ds_MerchantParameters);
      NSLog(redsys.Ds_SignatureVersion);
  
      [self.webView loadRequest:request];
  }
  </code></pre>