POST method in objective-C and PHP

I have created the following POST method via objective-C

-(IBAction) postLocation: (id) sender{
 NSString *latitude = @"37.3229978"; 
 NSString *longitude = @"-122.0321823";

 NSMutableURLRequest *request =[NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://www.mydomain.me/webservice.php"]];
 [request setHTTPMethod:@"POST"];

 NSString *post =[[NSString alloc] initWithFormat:@"latitude=%@longitude=%@submit",latitude,longitude];
 [request setHTTPBody:[post dataUsingEncoding:NSUTF8StringEncoding]];

NSURLResponse *response;
        NSError *err;
        NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningR开发者_如何学JAVAesponse:&response error:&err];
        }

and my PHP code is:

if (isset($_POST['submit']){

  //it doesn't get into this if statement
  $latitude = $_POST['latitude'];
  $longitude = $_POST['longitude'];

}

The question is, why can't the PHP code get into the if statement? Where can I state the 'submit' through objective-C?

Your query string for the POST does not contain the submit key. You should change it to the following

NSString *post =[[NSString alloc] initWithFormat:@"latitude=%@&longitude=%@&submit=",latitude,longitude];

No "&"s between the parameters.

-(IBAction) postLocation: (id) sender{

    NSString *latitude = @"37.3229978"; 
    NSString *longitude = @"-122.0321823";

    NSString *post = [NSString stringWithFormat:@"&latitude=%@&longitude=%@", latitude, longitude];

    NSData *postData = [post dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
    NSString *postLength = [NSString stringWithFormat:@"%d",[postData length]];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];

    NSString *address_url = @"http://www.mydomain.me/webservice.php?";

    address_url = [address stringByAppendingString:post];

    [request setURL:[NSURL URLWithString:[NSString stringWithFormat:address]]];
    [request setHTTPMethod:@"POST"];
    [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
    [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Current-Type"];
}

Probably, it is simpler to use if($_SERVER['REQUEST_METHOD'] == 'POST') instead of the code that you have now to check for form post.