File Upload to HTTP server in iphone programming

The code below uses HTTP POST to post NSData to a webserver. You also need minor knowledge of PHP.

NSString *urlString = @"http://yourserver.com/upload.php";
NSString *filename = @"filename";
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 *postbody = [NSMutableData data];
[postbody appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[postbody appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"userfile\"; filename=\"%@.jpg\"\r\n", filename] dataUsingEncoding:NSUTF8StringEncoding]];
[postbody appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
[postbody appendData:[NSData dataWithData:YOUR_NSDATA_HERE]];
[postbody appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[request setHTTPBody:postbody];

NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];
NSLog(@"%@", returnString);

ASIHTTPRequest is a great wrapper around the network APIs and makes it very easy to upload a file. Here's their example (but you can do this on the iPhone too - we save images to "disk" and later upload them.

ASIFormDataRequest *request = [[[ASIFormDataRequest alloc] initWithURL:url] autorelease];
[request setPostValue:@"Ben" forKey:@"first_name"];
[request setPostValue:@"Copsey" forKey:@"last_name"];
[request setFile:@"/Users/ben/Desktop/ben.jpg" forKey:@"photo"];

This is a great wrapper, but when posting to a asp.net web page, two additional post values need to be set:

    ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:url];
    //ADD THESE, BECAUSE ASP.NET is Expecting them for validation
    //Even if they are empty you will be able to post the file
    [request setPostValue:@"" forKey:@"__VIEWSTATE"];
    [request setPostValue:@"" forKey:@"__EVENTVALIDATION"]; 
    ///

    [request setFile:FIleName forKey:@"fileupload_control_Name"];
    [request startSynchronous];