Question

I have a method that should post some data to a PHP file:

-(void)submitForm {
    NSLog(@"name=%@", formName.text); // returns correct value

    NSString *post = [NSString stringWithFormat:@"name=%@&", formName.text];
    NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
    NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];

    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
    [request setURL:[NSURL URLWithString:@"http://path/to/file"]];
    [request setHTTPMethod:@"POST"];
    [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
    [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
    [request setHTTPBody:postData];

    NSURLResponse *response = NULL;
    NSError *requestError = NULL;
    NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&requestError];
    NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];

    NSLog(@"%@",responseString);
}

Note: I’m not actually using @"http://path/to/file". I’ve omitted the URL for privacy.

I believe it’s connecting to the PHP script correctly, since I’m receiving the response I expect. The problem is that if I echo out $name, I get an empty string. Here’s the script:

<?php
include("config.php"); // Handles DB connection
$name = mysql_escape_string($_POST["name"]);
mysql_query("insert into objects(name) values('$name')") or die(mysql_error());
echo $name; // returns empty string

All I expect is some sort of syntax/logic error in the Obj-C code, but I can’t spot it.

Answer 1

I’ve got a feeling that your request is missing some mandatory data, a boundary and content-type, which might lead to your POST request being half complete.

I’ll show you what I’ve done for uploading an HTML file to a webserver and then explain underneath.

Objective-C

NSString* str = formName.text;
NSData* theData = [str dataUsingEncoding:NSUTF8StringEncoding];
NSString *urlString = @"http://whereyouarepostingto.com";

NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];  
[request setURL:[NSURL URLWithString:urlString]];  
[request setHTTPMethod:@"POST"];  

NSString *boundary = @"---------------------------14737809831466499882746641449";  
NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@",boundary];  

[request addValue:contentType forHTTPHeaderField: @"Content-Type"];

NSMutableData *body = [NSMutableData data];  

[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary]   dataUsingEncoding:NSUTF8StringEncoding]];  
[body appendData:[[NSString stringWithString:[NSString stringWithFormat: @"Content-Disposition: form-data; name=\"file\"; filename=\"%@.html\"\r\n", self.fileName]] dataUsingEncoding:NSUTF8StringEncoding]];  
[body appendData:[@"Content-Type: application/octet-stream\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[NSData dataWithData:theData]];
[body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];  
[request setHTTPBody:body];  

NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];  
NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding]; 

NSLog(@"%@", returnString);

PHP

   <?php

    echo "Connection made to server";

    move_uploaded_file($_FILES["file"][tmp_name], "uploads/" . $_FILES["file"]["name"]);  

    ?>

You’ll need to change a few things around to fit your SQL insert and strip out my file stuff, but it’s a start.

This is the part I think you’re missing.

NSString *boundary = @"---------------------------14737809831466499882746641449";  
NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@",boundary];

The boundary can be a series of random numbers, but it has to exist.

Also, watch out when constructing the body of the request, especially the slashes. Make sure you escape any ” “.