NSURLConnection to upload file asynchonrously? - objective-c

Question

I'm kinda of new at ios development,
I've been reading and searching but cannot find a working example or an example of
how to upload a file from iphone to webserver asychronously..
I'm able to upload synchronously using
[NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
it works, but it blocks my main thread.
NSUrlConnection has this delegate (connection:didSendBodyData:totalBytesWritten:totalBytesExpectedToWrite:)
but I've no idea how to implement it.
Can someone please point me in the right direction?

Answer 1

I have managed to get uploading to work with NSURLConnection asynchronously with this:
-(NSURLRequest *)postRequestWithURL: (NSString *)url
data: (NSData *)data
fileName: (NSString*)fileName
{
// from http://www.cocoadev.com/index.pl?HTTPFileUpload
//NSMutableURLRequest *urlRequest = [NSMutableURLRequest requestWithURL:url];
NSMutableURLRequest *urlRequest = [[[NSMutableURLRequest alloc] init] autorelease];
[urlRequest setURL:[NSURL URLWithString:url]];
//[urlRequest setURL:url];
[urlRequest setHTTPMethod:#"POST"];
NSString *myboundary = [NSString stringWithString:#"---------------------------14737809831466499882746641449"];
NSString *contentType = [NSString stringWithFormat:#"multipart/form-data; boundary=%#",myboundary];
[urlRequest addValue:contentType forHTTPHeaderField: #"Content-Type"];
//[urlRequest addValue: [NSString stringWithFormat:#"multipart/form-data; boundary=%#", boundry] forHTTPHeaderField:#"Content-Type"];
NSMutableData *postData = [NSMutableData data]; //[NSMutableData dataWithCapacity:[data length] + 512];
[postData appendData:[[NSString stringWithFormat:#"\r\n--%#\r\n", myboundary] dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[[NSString stringWithFormat:#"Content-Disposition: form-data; name=\"userfile\"; filename=\"%#\"\r\n", fileName]dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[[NSString stringWithString:#"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
[postData appendData:[NSData dataWithData:data]];
[postData appendData:[[NSString stringWithFormat:#"\r\n--%#--\r\n", myboundary] dataUsingEncoding:NSUTF8StringEncoding]];
[urlRequest setHTTPBody:postData];
return urlRequest;
}
usage is as follows:
NSURLRequest *urlRequest = [self postRequestWithURL:urlString
data:aVideo.msgvid
fileName:filename];
uploadConnection =[[NSURLConnection alloc] initWithRequest:urlRequest delegate:self];

Answer 2

Threading is not necessary for this kind of problem. I would suggest you use the asynchronous functionality built into NSURLConnection:
NSURLConnection *connection = [NSURLConnection initWithRequest:request delegate:self];
[connection start];
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
//Get your response, do stuff
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
//Show error, retry, etc
}
EDIT: If you are really looking to upload a file and want to display a progress bar, then you should look at ASIHTTPRequest framework, which you can find more info on here: http://allseeing-i.com/ASIHTTPRequest/
For uploading a POST request with data using ASIHTTPRequest, you would do:
NSURL *url = [NSURL URLWithString:#"YOUR_URL_HERE"];
ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:url];
[request setPostValue:#"123" forKey:#"user_id"];
[request setData:someData withFileName:#"someData.jpg" andContentType:#"image/png" forKey:#"image"];
[request setProgressDelegate:self];
[request setDelegate:self];
[request startAsynchronous];
Again, refer to the link above for the framework and documentation. I highly recommend it.

Answer 3

You cant create new thread for that task:
[NSThread detachNewThreadSelector:#selector(upload:) toTarget:self withObject:data];
And when you will finish uploading, just call some implemented method in your main thread (for example uploaded):
[self performSelectorOnMainThread:#selector(uploaded) withObject:nil waitUntilDone:NO];