php web services not getting data from iphone application

Question

Hi, I am connecting with a php web service from my iphone application, I am doing a simple thing i.e. 1. Getting user inputs for: username password in a text field from the iphone form and sending the same to the PHP Post request web service. At the web service end I receive nothing other than blank fields that are inserted into the MySQL Database.......

The code for sample web service is:

**********************SAMPLE CODE FOR WEB SERVICES**************
<?php 
$con=mysql_connect("localhost","root","123456") or die(mysql_error());

mysql_select_db("eventsfast",$con);

$username = $_REQUEST['username'];
$password = $_REQUEST['password'];

echo $username;
echo $password;

$data = $_REQUEST;



$fp = fopen("log.txt", "w");
fwrite($fp, $data['username']);
fwrite($fp, $data['password']);

$sql="INSERT INTO users(username,password) VALUES('{$username}','{$password}')";

if(!mysql_query($sql,$con))
{
die('Error:'.mysql_error());
}

echo json_encode("1 record added to users table");
mysql_close($con);

echo "test";
?> 
******************************PHP***************** **************

*****************************IPHONE EVENT CODE******************
#import "postdatawithphpViewController.h"

@implementation postdatawithphpViewController
@synthesize userName,password;
-(IBAction) postdataid) sender
{
NSLog(userName.text);
NSLog(password.text); 
NSString * dataTOB=[userName.text stringByAppendingString:password.text];
NSLog(dataTOB);
NSData * postData=[dataTOB dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];

NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];
NSLog(postLength);
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http://localhost:8888/write.php"]];
[request setURL:url];
[request setHTTPMethod:@"POST"];
[request setValue:postLength forHTTPHeaderField:@"Content-Length"];
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
[request setHTTPBody:postData];

NSURLResponse *response;
NSError *error;
[NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];

if(error==nil)
NSLog(@"Error is nil");
else
NSLog(@"Error is not nil");
NSLog(@"success!");



} 

************************************************** ************** 

Please help.............