Question

I am posting an image from my IPhone app to a php page on a website using the code in this answer to this question. Essentially the code creates the correctly formatted html stream and submits it.

For Completeness, I have reposted the code.

- (BOOL)uploadImage:(NSData *)imageData filename:(NSString *)filename{


    NSString *urlString = @"http://www.yourdomainName.com/yourPHPPage.php";

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

    NSString *boundary = [NSString stringWithString:@"---------------------------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=\"userfile\"; filename=\"%@\"\r\n",filename]] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[NSData dataWithData:imageData]];
    [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];

    return ([returnString isEqualToString:@"OK"]);
}

However I’m not clever enough 🙁 to figure out how to add a general purpose field value eg. I would like to add a Comment field to be submitted along with the image file.

Any suggestions on how I could modify that code to add a number of fields to the POST form.

Thank you.

Update: I can get it to work by modifying the URL I post to to include GET Parameters, but I would rather use all post params.

Answer 1

It’s not too difficult. The general format of a multipart/form-data post is like this:

--boundary-string
Content-Disposition: form-data; name="field1"

value1
--boundary-string
Content-Disposition: form-data; name="field2"

value2
--boundary-string--

File uploads are a special case, but you already have that handled. To add another field, you just add another block. Something like this should do it:

NSMutableData *body = [NSMutableData data];

[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"Comment\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[comment dataUsingEncoding:NSUTF8StringEncoding]];

[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"userfile\"; filename=\"%@\"\r\n",filename] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[@"Content-Type: application/octet-stream\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[NSData dataWithData:imageData]];

[body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[request setHTTPBody:body];

BTW, you pretty much never need to call NSString’s stringWithString: method. If you need a copy, call copy, and otherwise just use the string you already have. NSMutableString’s stringWithString: can be useful as an alternative to [[string mutableCopy] autorelease] though.