Change NSURLConnection to NSURLSession for uploading images

Question

I currently upload images in the background to a server like this (the names get changed at the server to something better).

buildURL = [buildURL  stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSData *imageData = UIImageJPEGRepresentation(imageToUpload, 1.0);     //change Image to NSData

if (imageData != nil)
{
    NSString *filenames = [NSString stringWithFormat:@"imagename"];      //set name here
    NSLog(@"%@", filenames);
    NSString *urlString = buildURL;

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

    NSString *boundary = @"---------------------------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 stringWithFormat:@"Content-Disposition: form-data; name=\"filenames\"\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[filenames dataUsingEncoding:NSUTF8StringEncoding]];

    [body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
    [body appendData:[@"Content-Disposition: form-data; name=\"userfile\"; filename=\".jpg\"\r\n" 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]];
    // setting the body of the post to the reqeust
    [request setHTTPBody:body];
    // now lets make the connection to the web

    NSOperationQueue *queue = [[NSOperationQueue alloc] init];

    [NSURLConnection sendAsynchronousRequest:request queue:queue completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError)
            {

                NSString *returnString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
                NSLog(@"Returned From Image Upload : %@",returnString);
            }];

}

This works fine, I can see the images finish in the background no problem. The thing is I want to change this to use NSURLSession and the delegate didSendBodyData so that I can monitor the upload.

I have found a load of information about the download but none really about upload. I have tried to do this with the request BUT the completion block NEVER happens.. I have also tried using uploadTaskWithStreamedRequest but I can not get the delegate to happen...

    NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];

    NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfiguration delegate:self delegateQueue:nil];

    NSURLSessionDataTask *uploadTask = [session uploadTaskWithRequest:request fromData:imageData completionHandler:^(NSData *data, NSURLResponse *response, NSError *error)
                                          {
                                              NSLog(@"Image Uploaded ------------");
                                          }];

    [uploadTask resume];

I also found this StackOverflow 19985353 which seems to highlight some problems but I could really do with some example code. The image is picked from imagePicker if that helps.

I also tried both the answers here StackOverflow 19099448 but neither of them worked, again the block never executed. Is there something fundamental I am doing wrong with NSURLSession, a framework maybe! I also note I have no idea about the HTTP body which I have tried to play with but no luck.

Answer 1

Okay I did not realise that Session only works in iOS7 and above. To this end I have done a test and if iOS6 then I use NSURLConnection. The problem is I cannot get progress status from this (with the session I have an upload bar).

If anyone has any ideas about an upload progress bar using NSURLConnection then I would love to hear about it.

Answer 2

 NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL:_urlToUpload];// create request
    [request setHTTPMethod:@"POST"];// request type
     [request setTimeoutInterval:60];
    [request setValue:@"application/octet-stream" forHTTPHeaderField: @"Content-Type"];// content type
  NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];// configuration
    NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfiguration delegate:self delegateQueue:nil];// session

    NSURLSessionUploadTask *uploadTask = [session uploadTaskWithRequest:request fromFile:file completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) { }

Use the delegates


#pragma mark -
#pragma mark Session Upload Delegate Methods
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didSendBodyData:(int64_t)bytesSent totalBytesSent:(int64_t)totalBytesSent totalBytesExpectedToSend:(int64_t)totalBytesExpectedToSend {
    float status = (double)totalBytesSent / (double)totalBytesExpectedToSend;
    [[MTFileStreamer sharedFileStreamer] setCurrentStatus:status];
}

- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite {
}

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {
    NSLog(@"%s", __PRETTY_FUNCTION__);
}

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task willPerformHTTPRedirection:(NSHTTPURLResponse *)response
        newRequest:(NSURLRequest *)request completionHandler:(void (^)(NSURLRequest *))completionHandler {
    NSLog(@"%s", __PRETTY_FUNCTION__);
}

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge
 completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential *credential))completionHandler {
    NSLog(@"%s", __PRETTY_FUNCTION__);
}

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task needNewBodyStream:(void (^)(NSInputStream *bodyStream))completionHandler {
    NSLog(@"%s", __PRETTY_FUNCTION__);
}