ios Upload Image and Text using HTTP POST

Question

Thanks for reading.

I am new to iOS and I am trying to upload an Image and a text using multi-part form encoding in iOS.

The curl equivalent is something like this: curl -F "param1=value1" -F "[email protected]" "http://some.ip.address:5000/upload"

The curl command above returns the expected correct response in JSON.

Problem: I keep getting a HTTP 400 request which means I am doing something wrong while composing the HTTP POST Body.

What I Did: For some reference, I tried Flickr API iOS app "POST size too large!" and Objective C: How to upload image and text using HTTP POST?. But, I keep getting a HTTP 400.

I tried the ASIHttpRequest but had a different problem there (the callback never got called). But, I didn't investigate further on that since I've heard the developer has stopped supporting the library: http://allseeing-i.com/[request_release];

Could someone please help me out?

Answer 1

Here's code from my app to post an image to our web server:

// Dictionary that holds post parameters. You can set your post parameters that your server accepts or programmed to accept.
NSMutableDictionary* _params = [[NSMutableDictionary alloc] init];
[_params setObject:[NSString stringWithString:@"1.0"] forKey:[NSString stringWithString:@"ver"]];
[_params setObject:[NSString stringWithString:@"en"] forKey:[NSString stringWithString:@"lan"]];
[_params setObject:[NSString stringWithFormat:@"%d", userId] forKey:[NSString stringWithString:@"userId"]];
[_params setObject:[NSString stringWithFormat:@"%@",title] forKey:[NSString stringWithString:@"title"]];

// the boundary string : a random string, that will not repeat in post data, to separate post data fields.
NSString *BoundaryConstant = [NSString stringWithString:@"----------V2ymHFg03ehbqgZCaKO6jy"];

// string constant for the post parameter 'file'. My server uses this name: `file`. Your's may differ 
NSString* FileParamConstant = [NSString stringWithString:@"file"];

// the server url to which the image (or the media) is uploaded. Use your server url here
NSURL* requestURL = [NSURL URLWithString:@""]; 

// create request
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];                                    
[request setCachePolicy:NSURLRequestReloadIgnoringLocalCacheData];
[request setHTTPShouldHandleCookies:NO];
[request setTimeoutInterval:30];
[request setHTTPMethod:@"POST"];

// set Content-Type in HTTP header
NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@", BoundaryConstant];
[request setValue:contentType forHTTPHeaderField: @"Content-Type"];

// post body
NSMutableData *body = [NSMutableData data];

// add params (all params are strings)
for (NSString *param in _params) {
    [body appendData:[[NSString stringWithFormat:@"--%@\r\n", BoundaryConstant] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"\r\n\r\n", param] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithFormat:@"%@\r\n", [_params objectForKey:param]] dataUsingEncoding:NSUTF8StringEncoding]];
}

// add image data
NSData *imageData = UIImageJPEGRepresentation(imageToPost, 1.0);
if (imageData) {
    [body appendData:[[NSString stringWithFormat:@"--%@\r\n", BoundaryConstant] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithFormat:@"Content-Disposition: form-data; name=\"%@\"; filename=\"image.jpg\"\r\n", FileParamConstant] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[[NSString stringWithString:@"Content-Type: image/jpeg\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:imageData];
    [body appendData:[[NSString stringWithFormat:@"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
}

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

// setting the body of the post to the reqeust
[request setHTTPBody:body];

// set the content-length
NSString *postLength = [NSString stringWithFormat:@"%lu",(unsigned long) [body length]];
[request setValue:postLength forHTTPHeaderField:@"Content-Length"];

// set URL
[request setURL:requestURL];