NSData and Uploading Images via POST in iOS - iphone

Question

I have been combing through the many many posts about uploading images via POST in iOS. Despite the wealth of information on this topic, I cannot manage to correctly upload JPEG data taken from my iPhone Simulator Photo Library.
The data, once on the server, is just a huge string of hexidecimal. Shouldn't NSData just be a byte stream? I don't get whats going on with all the hex, or why this code seems to work for everyone else.
Here is the code in question:
-(void)uploadWithUserLocationString:(NSString*)userLocation{
NSString *urlString = #"http://some.url.com/post";
// set up the form keys and values (revise using 1 NSDictionary at some point - neater than 2 arrays)
NSArray *keys = [[NSArray alloc] initWithObjects:#"auth",#"text",#"location",nil];
NSArray *vals = [[NSArray alloc] initWithObjects:self.authToken,self.textBox.text,userLocation,nil];
// set up the request object
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
[request setURL:[NSURL URLWithString:urlString]];
[request setHTTPMethod:#"POST"];
//Add content-type to Header. Need to use a string boundary for data uploading.
NSString *boundary = [NSString stringWithString:#"0xKhTmLbOuNdArY"];
NSString *contentType = [NSString stringWithFormat:#"multipart/form-data; boundary=%#",boundary];
[request addValue:contentType forHTTPHeaderField: #"Content-Type"];
//create the post body
NSMutableData *body = [NSMutableData data];
[body appendData:[[NSString stringWithFormat:#"--%#\r\n",boundary] dataUsingEncoding:NSASCIIStringEncoding]];
//add (key,value) pairs (no idea why all the \r's and \n's are necessary ... but everyone seems to have them)
for (int i=0; i<[keys count]; i++) {
[body appendData:[[NSString stringWithFormat:#"Content-Disposition: form-data; name=\"%#\"\r\n\r\n",[keys objectAtIndex:i]] dataUsingEncoding:NSASCIIStringEncoding]];
[body appendData:[[NSString stringWithFormat:#"%#",[vals objectAtIndex:i]] dataUsingEncoding:NSASCIIStringEncoding]];
[body appendData:[[NSString stringWithFormat:#"\r\n--%#\r\n",boundary] dataUsingEncoding:NSASCIIStringEncoding]];
}
[body appendData:[[NSString stringWithString:#"Content-Disposition: form-data; name=\"image\"\r\n"] dataUsingEncoding:NSASCIIStringEncoding]];
[body appendData:[[NSString stringWithString:#"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSASCIIStringEncoding]];
[body appendData:[NSData dataWithData:self.imageData]];
[body appendData:[[NSString stringWithFormat:#"\r\n--%#--\r\n",boundary] dataUsingEncoding:NSASCIIStringEncoding]];
// set the body of the post to the reqeust
[request setHTTPBody:body];
// make the connection to the web
NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];
NSLog(returnString);
[keys release];
[vals release];
}
Thanks for your time.

Answer 1

This code works in my app. If you're not using ARC you'll need to modify the code to release anything alloc'ed.
// 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=%#", boundary];
[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", boundary] 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", boundary] 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", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
// setting the body of the post to the reqeust
[request setHTTPBody:body];
// set URL
[request setURL:requestURL];

Answer 2

i hope this code will help some body else ...
//create request
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
//Set Params
[request setHTTPShouldHandleCookies:NO];
[request setTimeoutInterval:60];
[request setHTTPMethod:#"POST"];
//Create boundary, it can be anything
NSString *boundary = #"------VohpleBoundary4QuqLuM1cE5lMwCy";
// set Content-Type in HTTP header
NSString *contentType = [NSString stringWithFormat:#"multipart/form-data; boundary=%#", boundary];
[request setValue:contentType forHTTPHeaderField: #"Content-Type"];
// post body
NSMutableData *body = [NSMutableData data];
//Populate a dictionary with all the regular values you would like to send.
NSMutableDictionary *parameters = [[NSMutableDictionary alloc] init];
[parameters setValue:param1 forKey:#"param1-name"];
[parameters setValue:param2 forKey:#"param2-name"];
[parameters setValue:param3 forKey:#"param3-name"];
// add params (all params are strings)
for (NSString *param in parameters) {
[body appendData:[[NSString stringWithFormat:#"--%#\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:#"Content-Disposition: form-data; name=\"%#\"\r\n\r\n", param] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:#"%#\r\n", [parameters objectForKey:param]] dataUsingEncoding:NSUTF8StringEncoding]];
}
NSString *FileParamConstant = #"imageParamName";
NSData *imageData = UIImageJPEGRepresentation(imageObject, 1);
//Assuming data is not nil we add this to the multipart form
if (imageData)
{
[body appendData:[[NSString stringWithFormat:#"--%#\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:#"Content-Disposition: form-data; name=\"%#\"; filename=\"image.jpg\"\r\n", FileParamConstant] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[#"Content-Type:image/jpeg\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:imageData];
[body appendData:[[NSString stringWithFormat:#"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
}
//Close off the request with the boundary
[body appendData:[[NSString stringWithFormat:#"--%#--\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
// setting the body of the post to the request
[request setHTTPBody:body];
// set URL
[request setURL:[NSURL URLWithString:baseUrl]];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
NSHTTPURLResponse* httpResponse = (NSHTTPURLResponse*)response;
if ([httpResponse statusCode] == 200) {
NSLog(#"success");
}
}];

Answer 3

Take a look at Apple's SimpleURLConnections example project. You can use the PostController from there with a few modifications.
However - it's not exactly simple. The difference to the solution above is that Apple's is using a stream to stream the file to the server. That's much more memory-friendly than keeping the encoded image data around for the duration of the upload. It's also way more complicated.

Answer 4

NSData *imgData = UIImagePNGRepresentation(imgUser.image);
NSString *str=[NSString stringWithFormat:#"%#upload_image",appDelegate.strRoot];
NSString *urlString = [NSString stringWithFormat:#"%#",str];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setURL:[NSURL URLWithString:urlString]];
[request setHTTPMethod:#"POST"];
NSMutableData *body = [NSMutableData data];
NSString *boundary = #"---------------------------14737809831466499882746641449";
NSString *contentType = [NSString stringWithFormat:#"multipart/form-data; boundary=%#",boundary];
[request addValue:contentType forHTTPHeaderField: #"Content-Type"];
[body appendData:[[NSString stringWithFormat:#"--%#\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[#"Content-Disposition: form-data; name=\"file\"; filename=\"a.jpg\"\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[#"Content-Type: application/octet-stream\r\n\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[NSData dataWithData:imgData]];
[body appendData:[#"\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
// parameter UserId
[body appendData:[[NSString stringWithFormat:#"--%#\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithFormat:#"Content-Disposition: form-data; name=\"userid\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[appDelegate.strUserID dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[#"\r\n" dataUsingEncoding:NSUTF8StringEncoding]];
// close form
[body appendData:[[NSString stringWithFormat:#"--%#--\r\n", boundary] dataUsingEncoding:NSUTF8StringEncoding]];
// setting the body of the post to the request
[request setHTTPBody:body];
NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
// NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];
NSDictionary *dict=[NSJSONSerialization JSONObjectWithData:returnData options:NSJSONReadingMutableLeaves error:nil];
NSLog(#"%#",dict);

Answer 5

I see that you send multiple files in one request, correct?
From HTTP specification, you should use multipart/mixed Content-type inside embedding multipart/form-data
Example from link above:
Content-type: multipart/form-data, boundary=AaB03x
--AaB03x
content-disposition: form-data; name="field1"
Joe Blow
--AaB03x
content-disposition: form-data; name="pics"
Content-type: multipart/mixed, boundary=BbC04y
--BbC04y
Content-disposition: attachment; filename="file1.txt"