Object reference not set to an instance of an object In XML - iphone

Question

I am new to iPhone and using XML in my application where i need to send one image to the server's one specific folder. For the same i am using the code :
NSString *filename = #"Image";
NSData *imageData = UIImageJPEGRepresentation([imageView image], 90);
NSString *urlString = [NSString stringWithFormat:#"http://111.111.11.1/webservices.asmx/PutImage"];
//url is : http://111.111.11.1/webservices.asmx/PutImage?ImgIn=image.jpg
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
[request setURL:[NSURL URLWithString:urlString]];
[request setHTTPMethod:#"POST"];
NSString *boundary = [NSString stringWithString:#"--------1473780983"];
NSString *contentType = [NSString stringWithFormat:#"application/x-www-form-urlencoded;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 stringWithFormat:#"Content-Disposition: form-data; name=\"images\"; filename=\"%#.jpg\"\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];
NSLog(#"\n\n\nreturnString : %#",returnString);
I am getting message like : "Object reference not set to an instance of an object" in return string. Can anybody guide me with some solution?

Answer 1

Ok... Try my code that i m using....
//imageview is a UIImageView
NSData *imageData = UIImageJPEGRepresentation(imageview.image, 100);
// setting up the URL to post to
NSString *urlString = #"http://example.com/upload";
// setting up the request object now
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
[request setURL:[NSURL URLWithString:urlString]];
[request setHTTPMethod:#"POST"];
/*
add some header info now
we always need a boundary when we post a file
also we need to set the content type
You might want to generate a random boundary.. this is just the same
as my output from wireshark on a valid html post
*/
NSString *boundary = [NSString stringWithString:#"---------------------------14737809831466499882746641449"];
NSString *contentType = [NSString stringWithFormat:#"multipart/form-data; boundary=%#",boundary];
[request addValue:contentType forHTTPHeaderField: #"Content-Type"];
/*
now lets create the body of the post
*/
NSMutableData *body = [NSMutableData data];
[body appendData:[[NSString stringWithFormat:#"\r\n--%#\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithString:#"Content-Disposition: form-data; name=\"userfile\"; filename=\".jpg\"\r\n"] 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]];
// setting the body of the post to the reqeust
[request setHTTPBody:body];
// now lets make the connection to the web
NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
self.returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];

Answer 2

To upload data from your iPhone to your server:
- (void)sendImage {
NSData *postData = [nsdata from your original image];
NSString *postLength = [NSString stringWithFormat:#"%d", [postData length]];
// Init and set fields of the URLRequest
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setHTTPMethod:#"POST"];
[request setURL:[NSURL URLWithString:[NSString stringWithString:#"http://yoururl.domain"]]];
[request setValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"Content-Type"];
[request setValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setHTTPBody:postData];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
if (connection) {
// Return data of the request
NSData *receivedData = [[NSMutableData data] retain];
}
[request release];
}