IOS connect to PHP webserver insert Data to mysql

I am trying to post a NSDictionary (encoded as Json format) to webserver (handled by php), in php, i am trying to decode json data and retrieve the variables one by one, then insert these variables into mysql DB here are some of my code:

    -(void)postTest{

    //build up the request that is to be sent to the server
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://localhost:8888/index.php"]];

    [request setHTTPMethod:@"POST"];
    [request addValue:@"postValues" forHTTPHeaderField:@"METHOD"];

    //create data that will be sent in the post
    NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] init];
    [dictionary setValue:@"p7878" forKey:@"id"];
    [dictionary setValue:@"tmd" forKey:@"first_name"];
    [dictionary setValue:@"nmb" forKey:@"last_name"];
    [dictionary setValue:@"goog" forKey:@"industry"];

    //serialize the dictionary data as json
    NSData *data = [[dictionary copy] JSONValue];

    [request setHTTPBody:data]; //set the data as the post body
    [request addValue:[NSString stringWithFormat:@"%d",data.length] forHTTPHeaderField:@"Content-Length"];

    NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
    if(!connection){
        NSLog(@"Connection Failed");
    }

}

i can see those data are post to webserver successfully. but somehow i cannot deserilized the json data and stored in different variables on php:

 <?php
// Create connection
$con=mysqli_connect("localhost","root","root","wenetwork");

// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }

if ($_SERVER['HTTP_METHOD'] === 'postValues'){ 
   $body;
   /*Sometimes the body data is attached in raw form and is not attached 
   to $_POST, this needs to be handled*/
   if($_POST == null){
      $handle  = fopen('php://input', 'r');
      $rawData = fgets($handle);
      $body = json_decode($rawData);
   }
   else{
      $body == $_POST;
   }



   echo json_encode($body);//just return the post you sent it for testing purposes


    $id = $body['id'];
    $first_name = $body['first_name'];
    $last_name = $body['last_name'];
    $industry = $body['industry'];


    $insertProfile = "INSERT INTO basic_profile (id, first_name, last_name, industry) VALUES ('". $id ."','". $first_name ."','". $last_name ."','". $industry ."')";

    mysqli_query($con, $insertProfile) or die (mysqli_error("Insert item's profile failed"));

    echo "Item added successfully!";
}
 mysqli_close($con);
?>

those $id, $firstname etc. are not able to hold correct data which sent from ios... therefore, when i excuted the sql statement, it doesn't work... can someone suggest me with solutions? cheers